Chemical Reaction & Equations (Objectives)
Q.31. Rancidity can be prevented by
(a) adding antioxidants
(b) storing food away from light
(c) keeping food in refrigerator
(d) all of these
Answer
Answer: dQ.32. The reaction of H2 gas with oxygen gas to form water is an example of
(a) combination reaction
(b) redox reaction
(c) exothermic reaction
(d) all of these reactions
Answer
Answer: aQ.33. The reaction in which two compound exchange their ions to form two new compounds is called
(a) displacement reaction
(b) combination reaction
(c) double displacement reaction
(d) redox reaction
Answer
Answer: cQ.34. On immersing an iron nail in CuSO4 solution for few minutes, you will observe
(a) no reaction takes place
(b) the colour of solution fades away
(c) the surface of iron nails acquire a black coating
(d) the colour of solution changes to green
Answer
Answer: dQ.35. An element X on exposure to moist air turns reddish-brown and a new compound Y is formed. The substance X and Y are
(a) X = Fe, Y = Fe2O3
(b) X = Ag, Y = Ag2S
(c) X = Cu, Y = CuO
(d) X = Al, Y = Al2O3
Answer
Answer: aQ.36.In the balanced equation – aFe2 O3 + bH2 → cFe + dH2 O The value of a,b,c,d are respectively – (A) 1,1,2,3 (B) 1,1,1,1 (C) 1,3,2,3 (D) 1,2,2,3
Answer
Answer: cQ.37.&Which of the following reactions is not balanced (A) 2NaHCO3 → Na2 CO3, + H2 O + CO2 (B) 2C4 H10 + 1202 → 8CO2 + 10H2 O (C) 2AI + 6H2O → 2AI (OH)3 + 3H2 (D) 4NH3 + 5O2 → 4NO + 6H2O
Answer
Answer: BQ.38.&The equation – Cu + xHNO3 → Cu(NO3 ) 2 + yNO2 + 2H2O The values of x and y are (A) 3 and 5 (B) 8 and 6 (C) 4 and 2 (D) 7 and 1
Answer
Answer: cQ.39.&Neutralization reaction is an example of – (A) exothermic reaction (B) endothermic reaction (C) oxidation (D) none of these
Answer
Answer: AQ.40.&Which of the following statements is/are true : (A) The total mass of the substance remains same in a chemical change. (B) A chemical change is permanent and irreversible. (C) A physical change is temporary and reversible. (D) All the these.
Answer
Answer: D