Which of the following would support the conclusion that a solid sample is a mixture?

A. the solid can be ground to a fine powder

B. the density of the solid is 2.25 g dm³

C. the solid has a melting range of 300^oC to 375^oC

D. the solid absorbs moisture from the atmosphere

The molar ratio of carbon to hydrogen of a volatile liquid compound is 1: 2. 0. 12 g of the liquid on evaporation at s.t.p. gave 32 cm³ of vapour. The molecular formula of the liquid is
[G.M.V =22.4 dm ³, C = 12, H = 1]

A. C ₃ H ₆

B. C ₄H ₈

C. C ₅C ₁₀

D. C ₆H ₁₂

20.00 cm ³ of a solution containing 0.53 g of anhydrous Na₂CO₃ in 100 cm³ requires 25.00 cm³ of H₂SO₄ for complete neutralisation. The concentration of the acid solution in moles per dm is [H =1, C = 12, O = 16, Na =23, S = 32]

A. 0.02

B. 0.04

C. 0.06

D. 0.08

The minimum volume of oxygen required for the complete combustion of a mixture of 10cm 3 of CO and 15 cm 3 of H 2 is

A. 25.0cm³

B. 12.5 cm³

C. 10.0 cm³

D. 5.0cm³

What is the partial pressure of hydrogen gas collected
over water at standard atmospheric pressure and 25 ^oC if the saturation vapour pressure of water at saturation vapour pressure of water is 23 mm Hg at that temperature?

A. 737 mm Hg

B. 763 mm Hg

C. 777 mm Hg

D. 783 mm Hg

The atomic radius of Li, Na and K are 1: 33A, 1. 54A and 1. 96A res pectively. Which of the following explaqins this gradation in atomic radius?

A. electropositivity decreases from Li to Na to K

B. electronegativity decreases from Li to Na to K

C. the number of the electron shells increases from Li to Na to K

D. the elements are in the same period

Elements X and Y have electronic configurations 1s\(^2\)2s\(^2\)2p\(^4\) and 1s\(^2\)2s\(^2\)2p\(^2\)3s\(^6\)3p\(^1\) respectively. When they combine, the formula of the compound formed is?

A. XY

B. YX

C. X₂Y₃

D. Y₂X₃

The atomic number of caesium is 55 and its atomic mass is 133. The nucleus of caesium atom therefore contains

A. 78 protons and 55 elections

B. 55 protons and 78 neutrons

C. 55 neutrons 78 electrons

D. 78 protons and 55 neutrons

Four elements P,Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively . Which of these electrons is a noble gas?

A. P

B. Q

C. R

D. S

How many valence electrons are contained in the element represented ³¹₁₅P?

A. 3

B. 5

C. 15

D. 31