The entropy change can be calculated by using the expression ΔS=qrevT
. when water freezes in a glass beaker, choose the correct statement amongst the following.
A.ΔS
(system) decreases but ΔS
(surroundings) remains the same
B.ΔS
(system) increases but ΔS
(surroundings) decreases
C.ΔS
(system) decreases but ΔS
(surroundings) increases
D.ΔS
(system) decreases but ΔS
(surroundings) also decreases

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)