Beryllium has higher ionisation enthalpy than boron. This can be explained as:A. Beryllium has higher size than boron hence its ionisation enthalpy is higherB. Penetration of 2p electrons to the nucleus is more than 2s electrons.C. It is easier to remove an electron from 2p orbital as compared to 2s orbital due to more penetration of s electrons.D. Ionisation energy increases in a period.

Which of the following is likely to be least stable?

• (A) Ca₄₀
• (B) Mn₅₅
• (C) Sn₁₁₉
• (D) Al₃₀

Which of the following is not a Lewis acid?

• A. BF₃
• B. AlCl₃
• C. FeCl₃
• D. PH₃

Which of the following is not a property of compounds?

• (A) They are made up of two or more kinds of atoms.
• (B) They cannot be broken down into two or more simpler substances by physical means but by chemical means only.
• (C) Properties of compounds differ from those of their elements.
• (D) None of the above.

Which of the following is polar?

• A. NF₃
• B. BF₃
• C. SF₄
• D. SiF₄

Which of the following metals exists in their native state in nature?

• (i) Ca
• (ii) Au
• (iii) Zn
• (iv) Ag

A. (i) and (ii)

B. (ii) and (iii)

C. (ii) and (iv)

D. (iii) and (iv)