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The p-Block Elements VVI Questions |Chemistry VVI Questions Class 12th | Chemistry Important Question Bihar Board | Bihar Board Chemistry Class 12th

The p-Block Elements VVI Questions

 

The p-Block Elements Subjective Questions

Q.1. Conc. HNO3 is stored in Aluminium vessel, Why ?

Ans – In presence of conc. HNO3 , Al becomes passive, due to a thin protective layer of its oxide (Al2O3) which is formed on its surface which prevents the further action between the metal and the acid. Therefore, Al containers can be used for storing conc. HNO3.

 

Q.2. Sulphur forms SF6 but not SCl6 , Why ?

Ans – Due to small size of S, six large Cl atoms cannot be accommodated around S atom. But small six F atoms can be easily accommodated around S atom to form SF6 . Moreover, because of low electronegativity of Cl, it cannot easily cause promotion of electrons in S to form S (VI).

 

Q.3. What is hybridisation of carbon in CH4 ?

Ans – The sum of number of sigma (σ) bonds and number of lone pair of electrons present in the valency shell of central-atom will give the hybridisation of that species. 

In CH4 carbon is bonded with four hydrogen atoms through four sigma (σ) bonds and has no lone pair of electrons. Its hybridisation is sp3, (i.e..1+3 = 4).

 

Q.4. HI, is stronger acid than HF. Explain.

Ans – The electronegativity difference between hydrogen and flourine is much more than that between hydrogen and iodine. Hence, H – I bond is weaker than H – F bond. So, HI can release proton (H) more readily than HF.

Hence HI is stronger acid than HF.

 

Q.5. Silicon shows only +4 oxidation state but tin shows both +2 and oxidation states both. Why ?

Ans – In +4 oxidation state, the compounds are covalent and in +2 state, the compounds are ionic. The lower valencies are more ionic because the radius of M2+ is greater than that of M4+ and according to Fajan’s rules, the smaller the cation, greater is the tendancy to covalency.

There is a decrease in stability of +4 oxidation state and increase in stability of +2 state on descending the group.

So, it can be concluded that s-electron pair of valency shell becomes more and more inert as one goes down the group, it is due to inert pair effect that stability of +4 oxidation decreases and that of +2 oxidation state increases.

Hence +4 state for Si and +2 state for Sn are more pronounced.

 

Q.6. HI, is stronger acid than HF. Explain.

Ans – The electronegativity difference between hydrogen and flourine is much more than that between hydrogen and iodine. Hence, H – I bond is weaker than H – F bond. So, HI can release proton (H) more readily than HF.

Hence HI is stronger acid than HF.

 

Q.7. H2S is a gas while H2O is liquid at room temperature.

Ans – Water exists as a liquid at room temperature with a high boiling point because sulphur is less electronegative than oxygen, so the S – H bond is much less polar than the O – H bond. Hence, there is no hydrogen bonding in hydrogen sulphide, and it normally exists as a gas with discrete H2S molecules.

 

Q.8. Carbon and silicon are tetravalent but Ge, Sn and Pb show divalency also.

Ans – Carbon (C), Silicon (Si), Germanium (Ge), Stannum (Sn / Tin) and Plumbum (Pb / lead) are all elements that belong to the P block of the periodic table. They have an electronic configuration of elements in ns2p2. The elements with large atomic numbers from divalent compunds due to innert pain effect while C and Si from tetravalent compunds.

 

Q.9. The electron affinity of flourine is less than that of Chlorine. Why ?

Ans – Electron affinity is the ability of an isloated gaseous atom to accept the electron in its outer most shell.

Though flourine is small in size and has higher affective nuclear charge density than chlorine, but has seven valency electrons in its small size, which cause repulsion. As a result the electron affinity of flourine becomes less than that of Chlorine.”

 

The p-Block Elements Objective Questions

“Q.1. Ammonia changes the moist red litmus paper into – 

(a) Blue

(b) Green

(c) Black

(d) White

Ans – (a) Blue

 

Q.2. Which of the following gas cannot be collected over water ?

(a) O2

(b) H2S

(c) SO2

(d) N2

Ans – (c) SO2

 

Q.3. The symbol of Helium is –

(a) He

(b) Hi

(c) Hm

(d) All

Ans – (a) He

 

Q.4. Second period of periodic table contains elements :

(a) 2

(b) 8

(c) 18

(d) 32

Ans – (b)8

 

Q.5. Number of (σ) sigma bonds in CH4 is – 

(a) 4

(b) 3

(c) 2

(d) 1

Ans – (a) 4

 

Q.6. PCl5 is a – 

(a) Oxidising agent

(b) Reducing agent

(c) Oxidizing and reducing agent both

(d) None

Ans – (a) Oxidising agent

 

Q.7. Nitrogen and Oxygen are – 

(a) Metals

(b) Non-metals

(c) Metalloids

(d) None

Ans – (b) Non-metals

 

Q.8. White and yellow phosphorus are – 

(a) Allotropes

(b) Isomers

(c) Isobars

(d) Isotones

Ans – (a) Allotropes

 

Q.9. Which of the following gas is mono-atomic ?

(a) Chlorine

(b) Helium

(c) Nitrogen

(d) Oxygen

Ans – (b) Helium

 

Q.10. Nitric acid is prepared by – 

(a) Contact process

(b) Ostwald’s method

(c) Photosynthesis

(d) Haber’s process

Ans – (b) Ostwald’s method

 

Q.11. Number of σ and π bonds in C2 molecule is/are –

(a) 1σ and 1π

(b) 1σ and 2π

(c) 2π only

(d) 1σ and 3π

Ans – (c) 2π only

 

Q.12. The molecule which has zero dipole moment is –

(a) NF3

(b) BF3

(c) ClO2

(d) CH2Cl2

Ans – (b) BF3

 

Q.13. Which of the following has the most stable +2 oxidation state ?

(a) Sn

(b) Ag

(c) Fe

(d) Pb

Ans – (d) Pb

 

Q.14. Which of the following gives yellow or brown precipitate with alkaline Nessler’s reagent ?

(a) CO2

(b) NH3

(c) NaCl

(d) Kl

Ans – (b) NH3

 

Q.15. Most stable oxidation state of bismuth is –

(a) +3

(b) +5

(c) +3 and +5 both

(d) None of these

Ans – (a) +3

 

Q.16. Which of the following oxides shows electrical properties like metals ?

(a) SiO2

(b) MgO

(c) SO2(s)

(d) CrO2

Ans – (d) CrO2

 

Q.17. Which of the following is an amorphous solid ?

(a) Graphite (C)

(b) Quartz Glass (SiO2)

(c) Chrome Alum

(d) Silicon Carbide (SiC)

Ans – (b) Quartz Glass (SiO2)

 

Q.18. When Quicklime is immersed in water, the reaction is –

(a) Exothermic

(b) Endothermic

(c) Explosive

(d) None of these

Ans – (a) Exothermic

 

Q.19. Shape of d-orbital is :

(a) Spherical

(b) Dumb-bell

(c) Double dumb-bell

(d) None of these

Ans – (c) Double dumb-bell

 

Q.20. Chemical name of borax is –

(a) Sodium tetraborate

(b) Sodium metaborate

(c) Sodium orthoborate

(d) None of the above

Ans – (a) Sodium tetraborate

 

Q.21. Boron shows diagonal relation with –

(a) Al

(b) C

(c) Si

(d) Sn

Ans – (c) Si

 

Q.22. Good conductor of electricity and heat is – 

(a) Anthracite coke 

(b) Diamond

(c) Graphite

(d) Charcoal

Ans – (c) Graphite

 

Q.23. In which of the following allotropes of carbon, percentage of carbon is maximum ?

(a) Wood charcoal

(b) Coconut charcoal

(c) Graphite

(d) None of these

Ans – (c) Graphite

 

Q.24. Organic compound must contain an element :

(a) Oxygen

(b) Carbon

(c) Hydrogen

(d) Nitrogen

Ans – (b) Carbon 

 

Q.25. Catenation property is maximum in –

(a) Phosphorus

(b) Carbon

(c) Sulfur

(d) Zinc

Ans – (b) Carbon

 

Q.26. Which one of the following act as electrophilic ?

(a) BF3

(b) NH3

(c) H2O

(d) None of these

Ans – (a) BF3

 

Q.27. Valency of carbon is –

(a) 1

(b) 2

(c) 3

(d) 4

Ans – (d) 4

 

Q.28. Criteria for purity of organic solid is –

(a) Boiling point

(b) Melting point

(c) Specific gravity

(d) None of these

Ans – (a) Boiling point

 

Q.29. Element found from sea water is – 

(a) Magnesium

(b) Sodium

(c) Iodine

(d) None of these

Ans – (c) Iodine

 

Q.30. The main constituent of CNG is –

(a) Methane

(b) Ethane

(c) Butane

(d) Isobutane

Ans – (a) Methane

 

Q.31. The shape of XeF4 is –

(a) Tetrahedral

(b) Square Planar

(c) Pyramidal

(d) Linear

Ans – (b) Square planar

 

Q.32. Which one of the following is the strongest Lewis acid ?

(a) BF3

(b) BCl3

(c) BBr3

(d) BI3

Ans – (d) BI3

 

Q.33. Which one of the following is least basic ?

(a) NCl3

(b) NBr3

(c) NI3

(d) NF3

Ans – (d) NF3

 

Q.34. Which one of the following does not form hydrogen bonding ?

(a) NH3

(b) H2O

(c) HCl

(d) HF

Ans – (c) HCl

 

Q.35. Which block of elements are known as transition elements ?

(a) p-block

(b) s-block

(c) d-block

(d) f-block

Ans – (c) d-block

 

Q.36. Sodium is a member of which group in periodic table ?

(a) Group 1

(b) Group 2

(c) Group 4

(d) None of these

Ans – (a) Group 1

 

Q.37. Most abundant element in earth’s crust is – 

(a) Si

(b) Al

(c) Zn

(d) Fe

Ans – (a) Si

 

Q.38. Modern pertiodic table is given by –

(a) Debonair

(b) Mendeleef

(c) Mendel

(d) None of these

Ans – (d) None of these

 

Q.39. Which one of the following is an alkal element ?

(a) Carbon

(b) Sodium

(c) Zinc

(d) Iron

Ans – (b) Sodium

 

Q.40. Main source of Helium is –

(a) Air

(b) Radium

(c) Monazite

(d) Water

Ans – (a) Air

 

Q.41. Which of the following is the strongest oxidising agent ?

(a) F2

(b) Cl2

(c) I2

(d) Br2

Ans – (a) F2

 

Q.42. Which of the following has maximum ionisation potential ?

(a) Al

(b) P

(c) Si

(d) Mg

Ans – (b) p

 

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