Subject

Chemistry

Class

NEET Class 12

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NEET Chemistry Solved Question Paper 2007

Multiple Choice Questions

What is the frequency of a X-ray photon whose momentum is 1.1 x 10^-23 kg-ms^-2?

5 x 10¹⁶ Hz
0.5 x 10²⁷ Hz
0.5 x 10¹⁸ Hz
5 x 10¹⁸ Hz

5 x 10¹⁸ Hz

E = mc²

E = hv

mc²= hv

$ν$ = $\frac{{mc}^{2}}{h}$ = $\frac{1.1 \times 10^{- 23} \times 3 \times 10^{8}}{6.6 \times 10^{- 34}}$

= 5 x 10¹⁸ Hz

The pH of a 0.02 M solution of HCl is :

1.7

0.02 M HCl = 2 x 10^-2 M HCl

[H⁺] = 2 x 10^-2

pH = - log[H⁺]

= - log [2 x 10^-2]

= - log 2 + 2 log 10

= - 0.3010 + 2

= 1.7

Heat of neutralisation of an acid with a base is 13. 7 kcal when :

both acid and base are weak
acid is weak and base is strong
both acid and base are strong
acid is strong and base is weak

both acid and base are strong

Heat of neutralisation for strong acid and strongbase is always close to 13.7 kcal .

$\underset{strong acid}{HA}$ + $\underset{strong base}{BOH}$ $⇌$ H₂O + AB

$∆$ H = - 13.7 Kcal

The heat of neutralisation of strong acid andstrong base is actually the heat of formation of1 gmole of water from 1 g of H⁺ and 1 g of OH^- .

Heisenberg's uncertainty principle can beexplained as :

$∆$ x $⩾$ $\frac{∆ p \times h}{4 π}$
$∆$ x x $∆$ p $⩾$ $\frac{h}{4 π}$
$∆$ x x $∆$ p $⩾$ $\frac{h}{π}$
$∆$ p $⩾$ $\frac{πh}{∆ x}$

$∆$ x x $∆$ p $⩾$ $\frac{h}{4 π}$

Heisenberg's uncertainty principle : It is notpossible to determine precisely both theposition and the momentum (or velocity) of asmall moving particle (e.g , electron , proton etc)

$∆$ x . $∆$ p $⩾$ $\frac{h}{4 π}$

where $∆$ x , $∆$ p are the uncertainties with regardto position , momentum respectively .

The geometry of methane molecule is :

tetrahedral
pyramidal
octahedral
square planar

tetrahedral

Methane (CH₃) shows the sp³ hybridisation .So , the geometry of methane molecule is tetrahedral .

The magnitude of orbital angular momentum ofan electron of azimuthal quantum number 2 is :

$\frac{2 h}{2 π}$
$\frac{\sqrt{6} h}{2 π}$
$\frac{\sqrt{2} h}{2 π}$
$\frac{6 h}{2 π}$

$\frac{\sqrt{6} h}{2 π}$

Orbital angular momentum = $\sqrt{l (l + 1)}$ $\frac{h}{2 π}$

where l = azimuthal quantum number

$\frac{\sqrt{6} h}{2 π}$

Hess's law is based on :

law of conservation of mass
law of conservation of energy
enthalpy is a state function
none of the above

law of conservation of energy

Hess's law is based upon conservation of energy .

The heat of formarion of CO₂ is - 393 kJ mol^-1 .The amount of heat evolved in the formation of0.156 kg of CO₂ .

- 1393 kJ
+ 1165.5 kJ
+ 1275.9 kJ
- 1165.5 kJ

- 1393 kJ

$∵$ Heat evolved during the formation of 44 g ofCO₂= - 93kJ

$∴$ Heat evolved in the formation of 0.156 kgof CO₂

= $\frac{- 393 \times 156}{44}$

= - 1393 kJ

9.
The bond energy is the energy required to :

dissociate one mole of the substance

dissociate bond in 1 kg of the substance

break one mole of similar bonds

break bonds in one mole of the substance

break one mole of similar bonds

Bond energy :It may be defined as the energyreleased when two atoms get bonded or it isequal to the energy required to break the bondto form the neutral atoms .

e.g , H-H (g) $\to$ H + H , $∆$ H = + 103 Kcal/mol