chemistry

The p-Block Elements eamcet mcq’s

1. On addition of conc. H2SO4 to a chloride salt, colourless fumes are evolved

but in case of iodide salt, violet fumes come out. This is because

(i) H2SO4 reduces HI to I2

(ii) HI is of violet colour

(iii) HI gets oxidised to I2

(iv) HI changes to HIO3

2. In qualitative analysis when H2S is passed through an aqueous solution of

salt acidified with dil. HCl, a black precipitate is obtained. On boiling the

precipitate with dil. HNO3, it forms a solution of blue colour. Addition of excess

of aqueous solution of ammonia to this solution gives _________.

(i) deep blue precipitate of Cu (OH)2

(ii) deep blue solution of [Cu (NH3)4]2+

(iii) deep blue solution of Cu(NO3)2

(iv) deep blue solution of Cu(OH)2.Cu(NO3)2

3. In a cyclotrimetaphosphoric acid molecule, how many single and double

bonds are present?

(i) 3 double bonds; 9 single bonds

(ii) 6 double bonds; 6 single bonds

(iii) 3 double bonds; 12 single bonds

(iv) Zero double bonds; 12 single bonds

4. Which of the following elements can be involved in pπ–dπ bonding?

(i) Carbon

(ii) Nitrogen

(iii) Phosphorus

(iv) Boron

6. Affinity for hydrogen decreases in the group from fluorine to iodine. Which of

the halogen acids should have highest bond dissociation enthalpy?

(i) HF

(ii) HCl

(iii) HBr

(iv) HI

8. On heating with concentrated NaOH solution in an inert atmosphere of CO2,

white phosphorus gives a gas. Which of the following statement is incorrect

about the gas?

(i) It is highly poisonous and has smell like rotten fish.

(ii) It’s solution in water decomposes in the presence of light.

(iii) It is more basic than NH3.

(iv) It is less basic than NH3.

9. Which of the following acids forms three series of salts?

(i) H3PO2

(ii) H3BO3

(iii) H3PO4

(iv) H3PO3

10. Strong reducing behaviour of H3PO2 is due to

(i) Low oxidation state of phosphorus

(ii) Presence of two –OH groups and one P–H bond

 (iii) Presence of one –OH group and two P–H bonds

(iv) High electron gain enthalpy of phosphorus

11. On heating lead nitrate forms oxides of nitrogen and lead. The oxides formed

are ______.

(i) N2O, PbO

(ii) NO2, PbO

(iii) NO, PbO

(iv) NO, PbO2

12. Which of the following elements does not show allotropy?

(i) Nitrogen

(ii) Bismuth

(iii) Antimony

(iv) Arsenic

13. Maximum covalency of nitrogen is ______________.

(i) 3

(ii) 5

(iii) 4

(iv) 6

14. Which of the following statements is wrong?

(i) Single N–N bond is stronger than the single P–P bond.

(ii) PH3 can act as a ligand in the formation of coordination compound

with transition elements.

(iii) NO2 is paramagnetic in nature.

(iv) Covalency of nitrogen in N2O5 is four.

17. On heating ammonium dichromate and barium azide separately we get

(i) N2 in both cases

(ii) N2 with ammonium dichromate and NO with barium azide

(iii) N2O with ammonium dichromate and N2 with barium azide

(iv) N2O with ammonium dichromate and NO2 with barium azide

18. In the preparation of HNO3, we get NO gas by catalytic oxidation of ammonia.

The moles of NO produced by the oxidation of two moles of NH3 will be ______.

(i) 2

(ii) 3

(iii) 4

(iv) 6

19. The oxidation state of central atom in the anion of compound NaH2PO2 will

be ______.

(i) +3

(ii) +5

(iii) +1

(iv) –3

22. Hot conc. H2SO4 acts as moderately strong oxidising agent. It oxidises both

metals and nonmetals. Which of the following element is oxidised by conc.

H2SO4 into two gaseous products?

(i) Cu

(ii) S

(iii) C

(iv) Zn

23. A black compound of manganese reacts with a halogen acid to give greenish

yellow gas. When excess of this gas reacts with NH3 an unstable trihalide is

formed. In this process the oxidation state of nitrogen changes from _________.

(i) – 3 to +3

(ii) – 3 to 0

(iii) – 3 to +5

(iv) 0 to – 3

24. In the preparation of compounds of Xe, Bartlett had taken O2

+ Pt F6

– as a base

compound. This is because

(i) both O2 and Xe have same size.

(ii) both O2 and Xe have same electron gain enthalpy.

(iii) both O2 and Xe have almost same ionisation enthalpy.

(iv) both Xe and O2 are gases.

27. Which of the following is isoelectronic pair?

(i) ICl2, ClO2

(ii) BrO2– , BrF2+

(iii) ClO2, BrF

(iv) CN–, O3