21. Which of the following statements about endothermic reaction is correct?
- A. Activation energy is high
- B. A catalyst is required
- C. It occurs reversibly
- D. Heat energy is absorbed
22. A 0.1\(moldm^{-3}\) solution of sodium hydroxide was diluted with distilled water to 0.001\(moldm^{-3}\). What is the dilution factor?
- A. 1000.00
- B. 100.00
- C. 10.00
- D. 0.01
23. Graphite and Diamond are similar in that they
- A. have octahedral shape
- B. have same density
- C. form carbon(IV) oxide on combustion
- D. conduct electricity
24. In a saturated solution at a given temperature, the undissolved solutes are in equilibrium with
- A. the solvent
- B. dissolved solute particles
- C. the saturated solution
- D. insoluble solute particles
25. The number of atoms present in 2.5moles of a triatomic gas is equivalent to [1mole = \(6.02\times 10^{23}\)]
- A. \(2.5\times 10^{23}\)
- B. \(1.5\times 10^{23}\)
- C. \(1.5\times 10^{24}\)
- D. \(2.5\times 10^{24}\)
26. When Magnesium reacts with oxygen, heat is
- A. alkalis
- B. acids
- C. bases
- D. salts
27. Which of the following gases is not acidic?
- A. \(SO_{3}\)
- B. \(NO_{2}\)
- C. \(Co_{2}\)
- D. CO
28. A hydrocarbon contained 14.3% hydrogen. The empirical formula for the hydrocarbon is [H= 1.0, C= 12.0]
- A. \(CH\)
- B. \(CH_{2}\)
- C. \(CH_{3}\)
- D. \(CH_{4}\)
29. Which of the following statements is NOT a chemical property of an acid?
- A. Evolution of ammonia when heated with ammonium salts
- B. Evolution of carbon dioxide gas when added to a trioxocarbonate (IV) salt
- C. Formation of salt and water with alkalis
- D. Formation of salt and hydrogen gas with reactive metals
30. Halogens generally react with metals to form
- A. alkalis
- B. acids
- C. bases
- D. salts
