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# NEET Chemistry Solved Question Paper 2012

#### Multiple Choice Questions

11.

Assertion : Diamond and graphite do not have the same crystal structure.

Reason : Diamond is crystalline while graphite is amorphous.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

C.

If assertion is true but reason is false.

In diamond, C-atoms are sp3 hybridized while in graphite, they are sp2 hybridized.

12.

Living in the atmosphere of CO is dangerous, because it

• combines with O, present inside to form CO2

• reduces organic matter of tissues

• combines with haemoglobin and makes it incapable to absorb oxygen

• dries up the blood.

C.

combines with haemoglobin and makes it incapable to absorb oxygen

Carbon monoxide combines with haemoglobin of blood to form a complex called carboxy-haemoglobin. Formation of this complex makes the haemoglobin incapable of oxygen transport. Due to which there will be oxygen deficiency in the blood.

13.

Assertion : Bohr model fails in case of multielectron pecies.

Reason : It does not mention electron-electron interactions.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

B.

If both assertion and reason are true but reason is not the correct explanation of assertion.

Bohr model does not explain the spectra of multi-electron atoms.

14.

Assertion : In a pressure cooker, the water is brought to boil. The cooker is then removed from the stove. Now on removing the lid of pressure cooker, the water starts boiling again.

Reason: The impurities in water bring down its boiling point.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

C.

If assertion is true but reason is false.

In pressure cooker, water boils above 100°C. When the lid of cooker is opened, pressure is lowered so that boiling point decreases and water boils again.

15.

For silicon which is not correct?

• It is a type of silicate.

• It is thermally unstable.

• It is hydrophilic.

• Repeating unit is R2SiO.

C.

It is hydrophilic.

Silicon is hydrophobic.

# 16.${\mathrm{S}}_{2}{\mathrm{O}}_{8}^{2-}$ haveS-S bond S-O bridge O-O bridge All S-O bond lengths are same.

C.

O-O bridge

The stmcture of peroxodisulfate anion is:

It has a O-O bridge.

17.

Assertion : Ois paramagnetic.

Reason : It has one unpaired electron.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

C.

If assertion is true but reason is false.

Oxygen has two unpaired electrons. So it is paramagnetic.

18.

If Si is doped with B,

• n-type semiconductor is formed

• p-type semiconductor is formed

• insulator is formed

• polymer is formed.

B.

p-type semiconductor is formed

Silicon belongs to group 14, it is doped with a group 13 element like B which contains only three valence electrons. The place where the fourth valence e is missing is called electron hole. Under the electric field, e holes moves toward the negatively charged plate, which implies that e- holes are positively charged, thus it is a p-type semiconductor.

19.

Assertion : ClFhas T-shape structure.

Reason : It has two lone pairs arranged at 180° angle.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false

C.

If assertion is true but reason is false.

ClF3 (T-shape)

The lone pairs are at equatorial position (120° angle).

20.

N-N bond length is minimum in

• N2O

• N2O3

• N2O4

• N2O5

A.

N2O

N-N bond lenght is minimum in N2O

 Compound Structure N2O N2O3 N2O4 N2O5