Chemistry Past Questions And Answers
What is the volume of oxygen required to bum completely 45cm3 of methane at s.t.p?
- A) 135.0cm3
- B) 180.0cm3
- C) 45.0cm3
- D) 90.0cm3
The main impurity in iron ore during the extraction of iron is
- A. Silicon (IV) oxide
- B. Carbon (IV) oxide
- C. Calcium trioxosilicate
- D. Sulphur (II) oxide
A mixture of sand, ammonium chloride and sodium chloride is best separated by _______
- A) sublimation followed by addition of water and filtration
- B) sublimation followed by addition of water and evaporation
- C) addition of water followed by filtration and sublimation
- D) addition of water followed by crystallization and sublimation
Which of the following describes the chemical property of acids?
- A) None of the above
- B) Acid + XCO3 → Salt + H2O + NH3
- C) Acid + NaOH →Normal salt + CO2
- D) Acid + XnCO3 → Salt + H2O + CO2
An increase in entropy can best be illustrated by
- A) mixing of gases
- B) freezing of water
- C) the condensation of vapour
- D) solidifying candle wax
A gas occupies 30.0dm3 at S.T.P. What volume would it occupy at 91°C and 380mmHg?
- A) 200.0dm3
- B) 40.0dm3
- C) 60.0dm3
- D) 80.0dm3
The energy required to remove the most loosely bound electron from an atom in the gaseous state is known as the
- A. bond energy
- B. ionization energy
- C. potential energy
- D. activation energy
Which of the following ions will give a white precipitate with aqueous NaOH and soluble in excess of the base?
- A. Ca2+
- B. Mg2+
- C. Zn2+
- D. Cu2+
The nitrogen obtained from air has a density higher than the one from nitrogen-containing compounds because the one from air is contaminated with
- A) water vapour
- B) oxgyen
- C) rare gases
- D) carbon (IV) oxide
When 70cm3of 3.0 moldm3 Na2CO3 is added to 30cm3 of 1.0moldm3 NaHCO3,the concentration of Na+ ions in moldm?3 in the solution is
- A) 1.5
- B) 4.5
- C) 2.0
- D) 3.5