Chemistry part 2 new pairing scheme 2018 for all boards.

Chemistry part 2 new pairing scheme 2018 for all boards

 Q.1 
One mcq  from all chapters and 2 mcqs from ch.16

Short Questions

Q.2
Attempt 8/12 S.Q ch.1=2, ch.2=1' ch.3=3, ch.4=3, ch.7=1, ch.16=2
Q.3
Attempt 8/12 S.Q two s.q from each ch.6, 8,11,12 and 13.one S.Q from each ch.9 and 10
Q.4
 Attepmt 6/9 S.Q
three  s.q from each ch.5, 14 and 15

Long questions

Attempt 3/5 L.Q
Q.5   1+2.
Q.6   6+16.
Q.7   7+9.
Q.8   8+11.
Q.9   10+12.
Regards.
Online Entry test academy

MDCAT Chemistry Lec#2,Topic UHS 1A,Fundamental Concepts(Mass Spectrometer)

c) MASS SPECTROMETER

An instrument which is used to measure the exact masses of different isotopes of an element together with their relative abundances is called mass spectrometer.

  Types of mass spectrometer

 •  Aston's mass spectrometer

 it was designed to identify isotopes of an element on the basis of atomic masses.

 •  Dempster's mass spectrometer

 it was designed to identify isotopes of an element which are in the solid state.

Parts of modern mass spectrometer       •   Vaporization chamber

•   Ionization chamber 

•   Electrical field acceleration 

•   Magnetic field deflection 

•   Ion collector detection 

•   Recorder 

•   Amplifier 

 The first five parts are present in gan

Dempster's mass spectrometer while last two parts are additional present in modern spectroscope.

Instrumentation of Dempster's mass spectrometer

    It has following five main parts.

Vaporization chamber 

      In this Chamber the sample of the element is vaporized and the vapour pressure is reduced to 10^-7 to 10^- 6 torr.

Ionization chamber

     In this chamber sample of the element is ionized either by alpha rays or by electron beam.

e-  +  X ------> X+  +  e-   +   e-

Electrical field 

     Electrical field is applied to accelerate the positive ion.The applied potential difference is of 500-2000 volts.

Magnetic field 

      On passing through magnetic field,deflection of positive ions take place according to their mass/charge ratio.

Formula

                   m/e = Hr/E

Electrometer or ion collector

 Ion collector receives positive ions according to their mass/charge ratio related to isotopes.

1. The strength of current measured by ion collector gives the relative abundance of ions of a definite m/e value.

2. The to the same experiment is performed with C-12 isotope and the current strength is compared.

Other techniques for the separation of isotopes 

•   Gaseous diffusion 

•   Thermal diffusion 

•   Distillation 

•   Ultracentrifuge 

•   Electromagnetic separation 

•   Laser separation

Examples 

i) Mass spectrum of Neon 

• The number of isotopes

 The three peaks in the mass spectrum show that neon contain three isotopes with the relative isotopic masses 20,21 and 22 respectively 

• The abundance of isotopes

 The relative heights of of the peaks give a direct measure of the relative abundances of the isotopes.

 ii) Mass spectrum for Boron
•   Number of isotopes
 The two peaks in the mass spectrograph shows that there are two isotopes of Boron with relative isotopic masses of 10 amu and 11 amu on the carbon-12 scale.
•   Abundance of the isotopes 
The relative height of the peaks give a direct meaure of the relative abundance of the isotopes.

•   Working out the relative atomic mass 
Suppose there are 123 typical atoms of Boron. 23 of these would be be B-10 and 100 would be be B-11.The total mass of these would be
 =  23 × 10 + 100 × 11 = 1330
 The average mass of these 123 atoms would be
= 1330/123 = 10.8 (to a significant figures)
•  10.8 is the relative atomic mass of Boron. A simple average of 10 and 11 is of course 10.5.Our answer of 10.8 allows for the fact that there are a lot of more of the heavier isotope of Boron and so the weighted average out to be closer to that.
 iii) Mass spectrum of chlorine
 The ions formed from chlorine elements are Cl2+ in the mass spectrum.These ions do not be particularly stable, and some will fall apart to give a chlorine atom and a Cl+ ion. This is term as fragmentation.
     Cl2+    --------> Cl  +   Cl+
 •  If the chlorine atom formed is not then ionized in the ionization chamber it's simply gets lost in the machine neither accelerated nor the deflected.
•  The Cl+ ions will pass through the machine and will give lines at 35 and 37 depending on the isotope and you would get exactly the pattern in the last diagram. • The problem is that we also observe lines for the unfragmented Cl2+ commented Cl2+ ions.
• The possible combinations of chlorine 35 and chlorine-37 atoms in the Cl2+ ions as
i) Both atoms in Cl2+ could be Cl-35 with relative mass of 70.
ii) Both atoms in Cl2+ could be Cl-37 with relative mass of 74.
iii) One atom in Cl2+ could be Cl-35 and second atom could be Cl- 37 with the relative mass of 72.
Total masses of the three possible Cl2+ could be of:
35 + 35 = 70
35 + 37 = 72
37 + 37 = 74

Conclusion
We will have two sets of lines.
1. Two lines for monatomic ions at m/z= 35 and 37 respectively,indicating that it has two isotopes.The realtive heights of the peaks at m/z =  35 and 37 are in the ratio 3:1.
2. Three lines for molecular ions at m/z = 70,72 and 74 respectively.The relative heights of the peaks at m/z =  70,72 and 74 are in the ratio 9:6:1.
 The overall mass spectrum is as follows

MDCAT Lec#1,UHS Topic 1A,Fundamental Concepts

ATOM

The smallest particle of an element which takes part in the chemical reaction is called an atom.

May exist independently

 Examples 

Monatomic gases

    •   Helium   (He)

    •   Neon       (Ne)

    •   Argone   (Ar)

 May not exist independently

 Example

    •  Hydrogen  (H2)

    •  Oxygen       (O2)

    •  Nitrogen     (N2)

a) RELATIVE MASS

 Relative mass is the mass of a given substance scaled with carbon- 12.

C-12 is used as standard in this scale because

1. It is highly stable isotope

2. Its mass is exactly in whole numbers that is 12.000

3. It can be handled easily

Relative atomic mass

The mass of an atom of an element as compared to the mass of an atom of carbon- 12 

Atomic mass unit (amu)

The unit is used to express relative atomic mass is called atomic mass unit (a.m.u) and it is 1/12 of the mass of one atom of C -12.

          1 a.m.u   =  1.661 × 10^- 27 kg 

          1 a.m.u   =  1.661 × 10^-24 g

 Examples 

i) Chlorine

 Isotopes                             Cl-35            Cl-37

Relative abundance          75%             25% i) Relative isotopic mass 17Cl-35 = 35 amu ii) Relative isotopic mass 17Cl-37 = 37 amu

iii) Relative atomic mass = 

Relative isotopic mass × R A + relative isotopic mass × RA/100

iv) Relative atomic mass of Cl = 35 × 75 + 37 × 25 /100 

= 26.25 + 9.25 = 35.5 amu

ii) Neon

Isotopes      10Ne-20       10Ne-21     10Ne-22

Relative 

abundance  90.92%        0.26%          8.82%

Relative atomic mass of Neon

= 20 × 90.92 + 21 × 0.26 + 22 × 8.82 /100 

= 20.18 amu

Relative isotopic mass

 The mass of an isotope of an element as compared to the mass of an atom of carbon - 12

 Examples

i)  Relative isotopic mass of chlorine-35 is 35 amu

 ii) Relative isotopic mass of chlorine-37 is 37 amu 

Relative molecular mass

 The mass of a molecule as compared to the mass of an atom of carbon-12 Examples

i) Relative molecular mass of water is 18 amu

ii) Relative molecular mass of carbon dioxide is 44 amu

Relative formula mass

 The mass of a formula unit as compared to the mass of an atom of carbon-12 Examples 

i) Relative formula mass of NaCl is 58.5 amu

ii) Relative formula mass of Na2SO4 is 142 amu

b) CONCEPT OF MOLE

When relative mass of any substance represent in grams (g) is called one mole of substance or molar mass.

• The mole is related to mass,volume and number of particles of the given substance.

Examples:

There are four different chemical substances can be represent in moles.

i) Atom

Relative mass of Na atom = 23 amu

When it represent in grams it becomes

23 amu ----> 23 grams = One Mole or simply Mole = Molar atomic mass or Molar mass = One gram mole

ii) Molecule

Relative mass of H2O molecule = 18 amu

When it represent in grams it becomes

18 amu ----> 18 grams = One Mole or simply Mole = Molar molecular mass or Molar mass = One gram mole

iii) Formula Unit

Relative formula mass of NaCl = 58.5 amu

When it represent in grams it becomes

58.5 amu ----> 58.5 grams = One Mole or simply Mole = Formula unit mass or Molar mass = One gram mole

iv) Ion

Relative mass of H+ ion = 1.008 amu

When it represent in grams it becomes

1.008 amu ----> 1.008 grams = One Mole or simply Mole = Molar ionic mass or Molar mass = One gram mole

We know according to Avogadro's 

One mole of any substance = NA = 6.02 × 10^23 particles (atoms or molecules or formula units or ions)

In case of ideal gases one mole of ideal gase at STP (standard temperature and pressure) =Molar volume (Vm) = 22.414 dm3 = 6.02 × 10^23 atoms or molecules

Interconversion of different Quantities into Mole

i. Mass into Moles and vice versa

Moles (n) = Mass (m) / Molar mass (M)

ii. Number of particles into Moles

Moles(n) = Number of particles(N)/NA

iii. Volume of ideal gas into Moles

Moles (n) = Vol.(V)/Molar Vol.(Vm)

Relationship between different formulae

• m / Mr = N / NA
• m / Mr = V / Vm
• N / NA  = V / Vm

Multiple Choice Questions

Q.1  The 4.4 g CO2 occupies ___________ volume at STP

A)  22.414 dm3

B)  11.207 dm3

C)  2.2414 dm3

D)  4.4000 dm3

Q.2 How many total number of atoms and electrons are present in 1.8 g of NH4- ions

A) 3.01 × 10^23 and 1.2 NA

B) 6.01 × 10^22 and 12 NA

C) 1.20 × 10^23 and 1.1 NA

D) 6.01 × 10^23 and 11

Q.3 The total number of molecules are present in 0.5 mole N2 gas?

A) 6.02 × 10^23

B) 3.01 × 10^23

C) 1.2 × 10^24

D) 1.5 × 10^ 23

Q.4 How many number of atoms are present in 0.5 mole of nitrogen gas?

A) 6.02 × 10^23

B) 3.01 × 10^23

C) 1.2 × 10^24

D) 1.5 × 10^ 23

Q.5 Thee mass of 1/2 mole of nitrogen gas is

A) 7 g

B) 14 g

C) 28 g

D) 56 g

Q.6 The largest number of moles are present in

A) 3.6g H2O

B) 2.8g CO

C) 4.8g C2H5OH

D) 5.4g N2O5

Q.7 Gram atoms of He in 8.0 g He gas

A) 1 gram

B) 2 gram

C) 4 gram

D) 8 gram

Q.8 22414 cm3 volume of Hydrogen gas at STP contains number of hydrogen atoms

A) 1 NA

B) 1.5 NA

C) 2 NA

D) 4 NA

Q.9 All of the followings are relative isotopic mass of Ne except

A) 20 amu

B) 21 amu

C) 22 amu 

D) 20.18 amu

Q.10  1 a.m.u is equal to

A) 1.661 × 10^-27 g

B) 1.661 × 10^ -24 g

C) 1.661 × 10^ -19 g

D) 1.661 × 10^ -30 g 

Answers:

1. C

2. A

3. B

4. A

5. B

6. A

7. B

8. C

9. D

10. B

Explanation:

1.

Use formula:

m / Mr = V / Vm

Or

V = m / Mr × Vm

V = 4.4 g / 44 g × 22.414 dm3

V = 0.1 × 22.414 = 2.2414 dm3

2.

Use formula for calculating total no.of atoms

N / NA = m / Mr × atomicity

Or

N = m / Mr × NA × 5

N = 1.8 g / 18 gmol-1 × 6.02 × 10^23 × 5

N = 0.1 × 6.02 × 10^23 × 5

N = 3.01 × 10^23 (Total atoms)

Use formula for calculating total no.of atoms

N / NA = m / Mr × No.of es- in one ion

Or

N = m / Mr × NA × 12

N = 1.8 g / 18 gmol-1 × 6.02 × 10^23 × 12

N = 0.1 × 6.02 × 10^23 × 12

N = 1.2 ×  6.02 × 10^23 or 1.2 NA (Total electrons)

Note: Explanation of remaining MCQs uploaded soon...

Biology ,Topic Cell Membrane Multiple Choice Questions

TOPIC#1 CELL BIOLOGY
Multiple Choice Questions on Membrane Transport MCQ

1. Gases such as oxygen and carbon dioxide cross the cell membrane by

a) passive diffusion through the lipid bilayer
b) primary active transport
c) specific gas transport proteins
d) secondary active transport

2.Carrier proteins are take part in
a) Water transport
b) Active transport of ions
c) Passive transport of ions
d) None of these

3. Which of the following is an example of primary active transport?
a) Cl--HCO3- exchange
b) Na+ K+ ATPase
c) Na+ - H+ exchange
d) Na+-Ca2+ exchange

4. The principal intracellular cation is:
a) Na+
b) Ca+
c) K+
d) Cl-

5. The sodium pump
a) Exchanges extracellular Na+ for intracellular K+
b) Is an ion channel
c) Is important for maintaining a constant cell volume
d) Can only be inhibited by metabolic poisons

6.  Which of the following values is closest to the resting membrane potential of mammalian cells:
a) +20 mV
b) -20 mV
c) -60 mV
d) +60 mV

7. Which of the following statements regarding exocytosis is correct?
a) Is always employed by cells for secretion
b) Takes up large molecules from the extracellular space
c) Allows the retrieval of elements of the cell membrane
d) Is used to deliver material into the extracellular space

8. Endocytosis is used by cells to:
a) Ingest bacteria and cell debris
b) Retrieve elements of the cell membrane after exocytosis
c) Secrete large molecules into the extracellular space
d) None of these

9.  Pinocytosis
a) At sites of membrane called coated pits.
b) For large  protein molecule
c) By formation   of pinocytic vesicle.
d) All of these

10. The resting membrane potential is mainly determined by:
a) the K+ gradient
b) the Cl- gradient
c) the Ca2+ gradient
d) the Na+ gradient

11. Which of the following process requires membrane proteins?
a) Pinocytosis
b) exocytosis
c) Phagocytosis
d) Receptor mediated endocytosis

12. Phagocytosis
a) Is preceded by opsonization
b) Requires presence of Ca2+ ions in extracellular fluid.
c) Occurs mainly in leucocytes
d) All of these

Answers:

1.a) passive diffusion through the lipid bilayer
2. b)Active transport of ions
3. b)Na+ K+ ATPase
4. c)K+
5. c)Is important for maintaining a constant cell volume
6. c)-60 mV
7. d)Is used to deliver material into the extracellular space
8. b)Retrieve elements of the cell membrane after exocytosis
9. d)All of these
10. a)the K+ gradient
11. d)Receptor mediated endocytosis
12. d)All of these

Video lecture & MCQs Chemistry F.Sc-I Ch#6 Chemical Bonding, Topic - Dipole Moment

Visit the following link for video lecture 

https://youtu.be/wfksQu1QYA4

Multiple Choice Questions (MCQs)

Q.1 Which of the following has maximum dipole moment value?

A) HF

B) HCl

C) HBr

D) HI

Q.2 The dipole moment value of H2O is

A) 1.4 D

B) 1.9 D

C) 1.09D

D) 2.24 D

Q.3 The dipole moment is the product of 

A) Distance and atomic number

B) Distance and charge

C) Electronegativity and charge

D) Distance and Electronegativity
Q.4 The dipole moment is zero for
A) HF
B) H2O
C) BF3
D) SO2
Q.5 The value of dipole moment gives information about
A) Bond angles in a molecule
B) Geometry of molecule
C) Type of molecule
D) Atomicity of molecule

Answers:

Q.1  A

Q.2  A

Q.3  B

Q.4  C

Q.5  B

Augmented reality education arloon

https://youtu.be/DXLyBQTS5-w

Chemistry 1st Year CH#8 Chemical Equilibrium Multiple Choice Questions

Multiple Choice Questions (MCQs)

Q.1  By increasing temperature of water from 25'C to 100 °C then  
A) The pH of water decreases
B) The pOH of water increases
C) The pKw of water remains constant
D) The pH of water remains constant

Correct Ans : A (The pH of water decreases]
Explanation : By increasing temperature the decomposition of water also increases the Kw of water increases approximately 75 times so its mean both [H+] ions and [OH-] ions increases
Kw = [H+] [OH-]  or pKw = pH + pOH
Hence we know:
pH = - log [H+]
if [H+] increases then pH decreases however pOH is also decreases because [OH-] ions are also  increases.Overall sum of H+ ions and OH- ions increases so Kw increases or pKw decreases.H+ and OH- ions equally increases so water is always neutral at any state.
Remember: by changing temp. Kw,pKw,pH,pOH.H+ and OH- all changes except neutrality of water remains constant.
Q.2  2SO2 + O2 <===> 2SO3   Delta H= -ve 
On increasing temperature of the above reaction then 
A) The concentration of SO2 decreases
B) The concentration of SO3 increases
C) The value of Kc increases
D) The rate of reaction increases

Correct Ans : D [The rate of reaction increases]
Explanation : The above reaction is reversiable exothermic reaction.According to kinetic theory and Arrhenius theory by increasing temperature the rate of reaction (exo or endo) always increases however in case of exothermic reaction the rate of backward direction increases as many times as compared to farward (forward also increases but with less speed). High temperature favours the overall backward direction so reactants increases and products decreases.
We know
Kc = [P]/ [R]
So Kc decreases on increasing temperature.

Chemistry F.Sc-II,Ch#10 Alkyl Halides

Multiple Choice Questions

Q.1 The hybridizatio of central carbon in transition state is?

A) sp

B) sp2

C) sp3

D) dsp2

 Q.2 The SN1 reactions are

A) zero order

B) 1st order

C) 2nd order

D) 3rd Order

 Q.3 The rate of SN1 reaction depends upon

A) Ionization

B) Conc.of RX

C) Slow step

D) All of above

 Q.4 The retention in structural configuration of RX in SN2 reactions is

A) 100%

B) 50%

C) 75%

D) 0%

 Q.5 which one of the following is common in SN1 & E1

A) Rate of reaction

B) Order of reaction

C) 1st step of ionization

D) Type of reaction

 Q.6 The characteristic reactions of alkyl halides are

A) Electrophilic substitution

B) Nucleophilic substitution

C) Beta elimination 

D) Addition

 Q.7 Ethyl bromide + Excess NH3 ------> ?

 *? in that above reaction is 

A) Ethyl amine

B) Diethyl amine

C) Triethyl amine

D) Tetraethylammine

 Q.8 The CH3-CH2-X is converted into ___________ on reaction with alcoholic KOH

A) Ethanol

B) Ethene

C) Ethanoic acid

D) Ethane

 Q.9 The all are primary alkyl halides except

A) n-Propyl chloride

B) Neo-pentyl chloride

C) iso-bytyl chloride

D) iso-propyl chloride

 Q.10 The complete products of following reaction are

CH3CH2OH + PBr3 -----> Products

A) CH3CH2Br + H3PO3

B) CH3CH2Br + POBr3 + HCl

C) CH3CH2Br + H3PO4

D) CH3CH2Br + H2O
Q.11 The best reducing agent can be used for complete reduction of Alkanoic acids is
A) NaBH4
B) LiAlH4
C) HI/P
D) H2/Ni

Answers:

1) B

2) B

3) D

4) D

5) C

6) B

7) A

8) B

9) D

10) A
11) C

EXPLANATION:
Q.1 
      When Alkyl halides reacts with nucleophile a transition state is formed in which carbon is plannar according to three hydrgen atoms with sp2 hybridization because in transition state the carbon is attached with three hydrogen atoms with single bond to each atom and one bond with halogen atom in the process of breaking and one bond with nucleophile in the process of formation so thses two bonds does not count to determine hybridization.Only complete bonds are considered to determine hybridization of central carbon atom in transition state.
Q.2
      The SN1 reaction is nucleophilic unimolecular reaction. It is two step process in which 1st step is slow and rate determining step.The order of reaction always depends upon rate determining step so SN1 reactions are 1st order because only alkyl halide is involved in rate determining step and rate depends upon only concentration of it.
      Rate = [Alkyl Halide]1
Q.3
      As explained above in Q.2 rate of SN1 reaction depends upon slow step,concentration of alkyl halide and ionization of tertiary alkyl halide.
Q.4
     The 100% inversion takes place in SN2 reactions so 0% retention takes place in SN2 reactions.
Q.5
     In both SN1 and E1 the first step is same i.e; ionization of tertiary alkyl halide molecule however in both reactions the second step is different i.e; nucleophilic substitution in SN1 and beta elimination in E1 reaction.
Q.6 
      The characteristics reactions of alkyl halid family are nucleophilic substitution reactions (SN)
Q.7
     If Ethyl bromide reacts with excess of ammonia it will produce primary ammine but if excess concentration of ethyl bromide reacts with ammonia it will produce quatanary ammine.If both are one mole each than primary alkyl halide will produce.
Q.8
      The Ethyl halide is converted into alkenes by reacting with alc.KOH (Alcoholic KOH) but it will converted into alcohol if reacts with Aq.KOH(Aqueous KOH).
Q.9
     Iso-propyl chloride is secondary alkyl halide.
Q.10
       Ehyl bromide and phosphorous acid (H3PO3) are products when ethyl bromide reacts with PBr3.
Q.11
       HI/P (Hydrogen iodide in the presence of red phosphorous) is strong reducing agent is used to convert carboxylic acids(alkanoic acids) into alkanes on complete reduction. But with LiAlH4 carboxylic acids are only partially reduced into alcohols.

Chemistry F.Sc-I Ch# 5,Multiple Choice Questions

Multiple Choice Questions (MCQs)

Q.1 The quantum number which is not derived from Schrödinger wave equation is?
A) Principal
B) Azimuthal
C) Magnetic
D) Spin
 Q.2 The total number of electrons can be accommodated in 5th shell of an atom are
A) 2
B) 18
C) 32
D) 50
 Q.3 The formula is used to calculate number of orbitals in a subshell is
A) n^2
B) 2l + 1
C) 2(2l + 1)
D) l = n - 1
 Q.4 The electronic configuration of one of the following atom does not follows Hund's rule
A) F
B) O
C) N
D) P
 Q.5 The quantum number is used to describe orientation of orbitals is
A) n
B) l
C) m
D) s
Q.6 The greater value of (n + l) is for
A) 3d
B) 4s
C) 5p
D) 4f
 Q.7 The least no.of electrons are present in the valence shell of
A) Zn
B) Cu
C) Ca
D) Cl
 Q.8 The volume of space in which there is ________ chance of finding an electron is called atomic orbital
A) 80%
B) 90%
C) 95%
D) 99%
 Q.9 The electron goes into______ subshell after filling 5p subshell
A) 4f
B) 6s
C) 4d
D) 4p
 Q.10 The shape of d-subshell is
A) Spherical
B) Dumble
C) Bilobed dumble
D) Complicated

Answers:
1)  D
2)  D
3)  B
4)  A
5)  C
6)  D
7)  B
8)  C
9)  B
10) C

Explanation:

Q.1

      The Schrodinger wave equation is derived for the division of area or space around the nucleus into shells,subshells and orbitals.The spin quantum number (s) does not about area or space around the nucleus of an atom but it is related to spinning of electron around its own axis i.e; self rotation so Schrodinger did not derived spin quantum number from his wave equation.

Q.2

      The formula is used to calculate total number of electrons in any shell is following

          2n^2

     n = shell number

If n = 5 

Then

Total electrons in 5th shell

= 2(5)^2 = 2(25) = 50 electrons

Q.3

      2l + l is the formula used to calculate number of orbitals in any subshell(azimuthal quantum number(l))

Q.4

      The electronic configuration of Fluorine (F) atom can be write without applying Hund's rule.Just try it yourself you will get the correct electronic configuration without applying Hinds rule

Q.5 

      The orientation of orbitals can be determined by using magnetic quantum number(m)

Q.6
          n        l       n+l
  3d    3       2      3+2= 5
  4s     4       0      4+0= 4
  5p    5       1      5+1= 6
  4f     4       3      4+3= 7

Q.7
    The electronic configurations
 Zn = [Ar] 3d^10 4s^2
 Cu = [Ar] 3d^10 4s^1
 Ca = [Ar] 4s^2
 Cl = [Ne] 3s^2 3p^5
    So its Cu which contains least( only one) electron in its outermost 4th shell

Q.8
     The volume of space in which there is more than 95% chance of finding an electron is called atomic orbital

Q.9
    According to n+l rule the next higher energy level after 5p is 6s

Q.10
     The shape of different sunshells
    Subshell                     Shape
         s                               Spherical
         p                              Dumble
         d                              Bilobed Dumble
         f                               Trilobed Dumble

Multiple Choice Questions F.Sc-I,Ch#5 Atomic Structure

Multiple Choice Questions F.Sc-I Ch#5 Atomic Structure

Q.1 Heisenberg's uncertainty principle is contradicted by?
A) Lewis concept
B) Bohr's atomic model
C) Rutherford's model
D) Hund's rule
 Q.2 The radius of 1st orbit of hydrogen by Bohr's atomic model is
A) 0.529 'A
B) 2.11 'A
C) 4.75 'A
D) 8.40 'A
 Q.3 The volume of space in which there is ________ chance of finding an electron is called atomic orbital
A) 80%
B) 90%
C) 95%
D) 99%
 Q.4 The greater the frequency of X-rays,________ will be the uncertainty in the momentum of electron
A) Greater
B) Shorter
C) Equal
D) Less
 Q.5 If an electron is moving with a velocity of 2.188 × 10^6 m/s in the 1st orbit of hydrogen atom,its wavelength will be
A) 4.5 × 10^-3 nm
B) 0.33 nm
C) 1.8 × 10^-13 m
D) 0.33 × 10^-9 nm

 Answers:
Q.1  B
Q.2  A
Q.3  C
Q.4  A
Q.5  B

Chemistry Multiple Choice Questions Ch# 7+8+9 F.Sc II

Q.1 Which one of the following is least reactive towards electrophilic substitution reaction?
A) Phenol
B) Benzene
C) Chlorobenzene
D) Toluene
 Q.2 The primary,secondary and tertiary structures of butyl alcohol are ___________ isomers of each other?
A) Positional
B) Functional group
C) Chain
D) Cis-Trans
 Q.3 The addition of HBr to propene follow
A) Markonikov's rule
B) Hund's rule
C) Pauli's rule
D) Aufbau
 Q.4 The General formula of alkynes is
A) CnH2n
B) CnH2n-2
C) CnHn
D) CnHn+2
 Q.5 Which one is more reactive? 
A) Benzene
B) Ethene
C) Ethyne
D) Ethane
Q.6 Which of the following is strictly hydrocarbons
A) Phenol
B) Toluene
C) Aniline
D) Pyridine

Answers:
Q.1 C
Q.2 A
Q.3 A
Q.4 B
Q.5 B
Q.6 B
Explanation: Hydrocarbons must contain only hydrogen and carbon elements that is why correct option is toluene (methyl benzene).Phenol,Aniline and pyridine contain oxygen,nitrogen and nitrogen respectively so these compounds are organic in nature but not strictly hydrocarbons.

Chemistry Multiple Choice Question

Q.1 Which one of the following is strongest oxidizing agent among the following?
A) HClO
B) HClO2
C) HClO3
D) HClO4
 Q.2 The noble gas is used in weather balloons?
A) He
B) Ne
C) Ar
D) Xe
 Q.3 The heaviest gas is
A) SO2
B) NO3
C) Rn
D) Cl2
Q.4 The gas used in bactericidal lamp is
A) He
B) Kr
C) Xe
D) Rn
Q.5 Which of the following is used as local anesthesia?
A) Halothane
B) Chloroform
C) Diethyl ether
D)Tetrachloromethane

 Answers
1. A
2. A
3. C
4. C
5. C
Explanation:
Q.1
     HClO is strongest oxidizing agent among the oxyacids of chlorine.
The oxiding power of HClO4, HClO3, HCLO2, HClO are in the following order:
HClO >HCLO2 >HClO3>HClO4
because the oxidizing power of oxyacids of chlorine is inversely related to the thermal stability of these acids i.e. higher the thermal stability, lower will be oxidizing power of the oxyacid and vice versa. For example the HClO4 is most stable so it has lowest oxidizing power amongst the oxyacids of chlorine. The order of thermal stability of oxyacids of chlorine is HClO4>HClO3>HClO2>HClO.
Q.2
     Helium(He) is lightest gas that is why it is used in whether balloons for measurement of atmospheric pressure and air direction.
Q.3
    Radon(Rn) is heaviest gas of the periodic table.It is heavy than SO2,NO2 and Cl2 gases.The molar mass of Rn us greater than all given gases i.e: Rn = 222 g/mol
Q.4
    Xenon (Xe) uses in bactericidal or germicidal lamps because it emits UV radiations which helps to kill bacteria or germs.
Q.5
Local anesthesia uses medicine to block sensations of pain from a specific area of the body. Local anesthetics are usually given by injection into the body area that needs to be anesthetized. They are not injected into the bloodstream (intravenous, IV).So diethyl ether is preferred to use as local anesthesia.However halothane,chloroform and carbontetrachlororide are also used as anesthetic chemicals.
   

Chemistry F.Sc Part-I,Ch#1 Topic-Combustion Analysis

ELEMENTAL ANALYSIS

• Introduction
• Types
• Combustion Analysis
• Formula
• Multiple Choice Questions

Introduction

   Elemental analysis is a process where a sample of some material (e.g., soil, waste or drinking water, bodily fluids, minerals, chemical compounds) is analyzed for its elemental and sometimes isotopic composition. Elemental analysis can be qualitative (determining what elements are present), and it can be quantitative (determining how much of each are present). Elemental analysis falls within the ambit of analytical chemistry, the set of instruments involved in deciphering the chemical nature of our world.

For organic chemists, elemental analysis or "EA" almost always refers to CHNX analysis—the determination of the mass fractions of carbon, hydrogen, nitrogen, and heteroatoms (X) (halogens, sulfur) of a sample. This information was very important to help determine the structure of an unknown compound, as well as to help ascertain the structure and purity of a synthesized compound. In present day organic chemistry spectroscopic technics (like NMR, both 1H and 13C), mass spectrometry and chromatographic procedures have replaced EA as the primary technique for structural determination, although it still gives very useful complementary information. It is also the fastest and most inexpensive method to determine sample purity.

Antoine Lavoisier is regarded as the inventor of elemental analysis as a quantitate, experimental tool to assess the chemical composition of a compound. At the time elemental analysis was based on gravimetric determination of specific adsorbant materials before and after selective adsorption of the combustion gases.[1][2] Today fully automated systems based on thermal conductivity or infrared spectroscopy detection of the combustion gases, or other spectroscopic methods are used.

Combustion Analysis

   Combustion analysis is a method used in both organic chemistry and analytical chemistry to determine the elemental composition (more precisely empirical formula) of a pure organic compound by combusting the sample under conditions where the resulting combustion products can be quantitatively analyzed. Once the number of moles of each combustion product has been determined the empirical formula or a partial empirical formula of the original compound can be calculated.

Applications for combustion analysis involve only the elements of carbon (C), hydrogen (H), nitrogen (N), and sulfur (S) as combustion of materials containing them convert these elements to their oxidized form (CO2, H2O, NO or NO2, and SO2) under high temperature high oxygen conditions. Notable interests for these elements involve measuring total nitrogen in food or feed to determine protein percentage, measuring sulfur in petroleum products, or measuring total organic carbon (TOC) in water.

Types of elemental analysis

   Quantitative analysis is the determination of the mass of each element or compound present.

   Qualitative analysis is to qualitatively determine which elements exist in a sample.

Formula

Multiple Choice Questions:

1. Amount of KOH used in combustion analysis
A) 50%
B) 60%
C) 70%
D) 80%

 A

2. Amount of oxygen in combustion analysis is determined by method of
A) Product
B) Difference
C) Addition
D) Division