Elements X and Y have electronic configurations 1s\(^2\)2s\(^2\)2p\(^4\) and 1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^1\) respectively. When they combine, the formula of the compound formed is?
- A. XY
- B. YX
- C. X2Y3
- D. Y2X3
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
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 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
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 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
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 300oC to 375oC
- D. the solid absorbs moisture from the atmosphere