Practice General concepts of chemistry - general science mcq Online Quiz (set-2) For All Competitive Exams
Q-1) Rusting of an iron is an example of
(a)
(b)
(c)
(d)
Rusting results in formation of iron oxide.
Q-2) The empirical formula of a compound is CH2 . One mole of this compound has a mass of 42 grams. Its molecular formula is :
(a)
(b)
(c)
(d)
Empirical formula of compound = $CH_2$ Molecular mass of the compound = 42 ∴ n = $42/14$ = 3 ∴ Hence molecular formula = $C_3H_6$
Q-3) An organic compound containing C, H and O gave on analysis C – 40% and H – 6.66%. Its empirical formula would be
(a)
(b)
(c)
(d)
| Element | % | At.Wt. | Rel.Number | Ratio | ||||
| C | 40 | 12 | $40/12$= 3.33 | ${3.33}/{3.33}=1$ | ||||
| H | 6.66 | 1 | ${6.66}/1$= 6.66 | ${6.66}/{3.33}=2$ | ||||
| O | 53.34 | 16 | ${53.34}/16$= 3.33 | ${3.33}/{3.33}=1$ |
Q-4) When electrons are added the resulting ion is called
(a)
(b)
(c)
(d)
Cl + e– Cl– (acidic radicals)
Q-5) An organic compound containing C, H and N gave the following analysis : C = 40% ; H = 13.33% ; N = 46.67% Its empirical formula would be
(a)
(b)
(c)
(d)
As the sum of the percentage of C, H & N is 100. Thus it does not contains O atom.
Table for empirical formula
| Element | % | At. Wt. | Rel.Number | Ratio | ||||
| C | 40.00 | 12 | $40/12$= 3.66 | ${3.66}/{3.33}=1.09 ∼ 1$ | ||||
| H | 13.33 | 1 | ${13.33}/1$= 13.33 | ${13.33}/{3.33}=4$ | ||||
| N | 46.67 | 14 | ${46.67}/14$= 3.33 | ${3.33}/{3.33}=1$ |
Q-6) Which one of the following is not an exothermic reaction ?
(a)
(b)
(c)
(d)
No reaction occurs in this case.
Q-7) The branch of chemistry which deals with study of the methods of detection and determination of elements and compounds is
(a)
(b)
(c)
(d)
Q-8) Valency of an atom or radicals is
(a)
(b)
(c)
(d)
Q-9) When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is formed. This is an example of
(a)
(b)
(c)
(d)
${CuSO_4} ↙{(Blue)} + H_2S ⟶ {CuS ↓} ↙(Black) + H_2SO_4$
Q-10) AgNO3(aq) + NaCl(aq) ⟶ AgCl(s) + NaNO3(aq) Above reaction is -
(a)
(b)
(c)
(d)
This reaction is double displacement and precipitation as well because insoluble silver chloride gets precipitated.
Q-11) Which of the following statements is true about chemical equation ?
(a)
(b)
(c)
(d)
Q-12) Which of the following statement is not correct ? To prevent food from getting rancid, we
(a)
(b)
(c)
(d)
Increase the temperature of the food.
Q-13) The empirical formula and molecular mass of a compound are CH2O and 180 g respectively. What will be the molecular formula of the compound ?
(a)
(b)
(c)
(d)
$n =180/\text"Molecular mass of CH_2O" = 180/30$n=6
Q-14) Select the one that represents a displacement reaction.
(a)
(b)
(c)
(d)
Q-15) The formula of sodium pyrophosphate is
(a)
(b)
(c)
(d)
Q-16) The molecular formula P2O5 means that
(a)
(b)
(c)
(d)
Q-17) Which of the following reaction is endothermic?
(a)
(b)
(c)
(d)
Heat is required to decompose calcium carbonate. Thus this reaction proceeds with absorption of heat therefore it is endothermic reaction.
Q-18) Which one is a decomposition reaction ?
(a)
(b)
(c)
(d)
In all these reactions the reactants decompose to form simpler products.
Q-19) Which one is a combination reaction ?
(a)
(b)
(c)
(d)
Sn + 2Cl2 SnCl4.
Q-20) Which of the following statements is not correct?
(a)
(b)
(c)
(d)