Chemistry - Matter and Laws of Chemical Combination
Exam Duration: 45 Mins Total Questions : 30
The solid like conducting state of gases with free electrons is called
- (a)
sol
- (b)
gel
- (c)
plasma
- (d)
All of these
which of the following statements about a compound is incorrect?
- (a)
A molecule of a compound has atoms of different elements
- (b)
A molecule of a compound has atoms of different elements
- (c)
A molecule of a compound has atoms of different elements
- (d)
A molecule of a compound has atoms of different elements
A molecule of a compound has atoms of different elements
- (a)
Mixture of soil and water
- (b)
Sugar solution
- (c)
Mixture of sugar, salt and sand
- (d)
Iodised table salt
In which of the following numbers all zeroes are significant?
- (a)
30.000
- (b)
0.700
- (c)
0.00050
- (d)
0.0030
The answer of the calculation \(\frac{2.568\times5.8}{4.168}\) in significant figures will be
- (a)
3.570
- (b)
3.6
- (c)
3.57
- (d)
3.579
Number of significant figures in 78.000 g, 0.0206 g and 3.002 g are
- (a)
3, 4, 5
- (b)
2, 5, 4
- (c)
3, 3, 4
- (d)
5, 3, 4
Law of constant composition does not hold true for
- (a)
endothermic compounds
- (b)
exothermic compounds
- (c)
stoichiometric compounds
- (d)
non-stoichiometric compounds
Formation of CO and CO2 illustrates the law of
- (a)
conservation of mass
- (b)
multiple proportion
- (c)
reciprocal proportion
- (d)
constant proportion
Which of the following reactions is not correct according to the law of conservation of mass?
- (a)
2Mg(s) + O2(s) \(\rightarrow\) 2MgO(s)
- (b)
C3H8(g) + O2 (g) \(\rightarrow\) CO2(g) + H2O(l)
- (c)
P4(s) + 5O2(g) \(\rightarrow\) P4O10(s)
- (d)
CH4(g) + 2O2(g) \(\rightarrow\) CO2(g) + 2H2O(g)
One part of element A reacts with two parts of another elements B. 6 parts of element C reacts with 4 parts of element B. If A and C combine together, the ratio of their weights will be governed by
- (a)
law of conservation of mass
- (b)
law of reciprocal proportions
- (c)
law of definite proportions
- (d)
law of multiple proportions
Molecular weight of a tribasic acid is W. Its equivalent weight will be
- (a)
W/2
- (b)
W
- (c)
W/3
- (d)
3W
Arsenic forms two oxides, one of which contains 65.2 % and the other contains 75.7% of the element. Hence, equivalent masses of arsenic are in the ratio.
- (a)
1 : 2
- (b)
3 : 5
- (c)
13 : 15
- (d)
2 : 1
The number of water molecules present in a drop of water (volume 0.0018 mL) at room temperature is
- (a)
1.084 x 1018
- (b)
6.023 x 1019
- (c)
4.84 x 1017
- (d)
6.023 x 1023
Number of molecules in 4.25 g of NH3 is
- (a)
1.505 x 1023
- (b)
6.02 x 1023
- (c)
3.01 x 1023
- (d)
None of these
Match the following and choose the correct option.
Column I | Column II |
A. 88 g of CO3 B.6.022 x 1023 molecules of H2O C.5.6 L of O2 at STP D. 1 mole of any gas |
1. 0.2 mol 2. 2 mol 3. 1 mol 4. 6.022 x 1023 molecules |
- (a)
A B C D 2 3 1 4 - (b)
A B C D 2 4 1 3 - (c)
A B C D 1 2 4 3 - (d)
A B C D 3 2 4 1
One gram mole of a gas at NTP occupies 22.4 L. This fact is derived from
- (a)
law of gaseous volumes
- (b)
Avogadro's hypothesis
- (c)
Dalton's atomic theory
- (d)
Berzelius hypothesis
Compounds having same empirical formula always have same
- (a)
law of gaseous volumes
- (b)
Avogadro's hypothesis
- (c)
Dalton's atomic theory
- (d)
Berzelius hypothesis
A sample of AlF3 contains 3.0 x 1024 F- ions. The number of formula units of this sample are
- (a)
9.0 x 1024
- (b)
3.0 x 1024
- (c)
0.75 x 1024
- (d)
1.0 x 1024
In a compound ABC, element A has oxidation number An-. It is oxidation to Aa+ by Cr2O72- in acidic medium. In the experiment, 1.68 x 10-3 moles of K2Cr2O7 were used for 3.36 x 10-3 moles of ABC. After oxidation, new oxidation numbeis of A0
- (a)
3
- (b)
+ n
- (c)
n - 3
- (d)
3 - n
Which of the following pairs contain equal number of atoms?
- (a)
22.4 L (STP) of nitrous oxide and 22.4 L of nitric oxide
- (b)
1 millimole of HCl and 0.5 millimole of H2 S
- (c)
1 mole of H2O2 and 1 mole of N2O4
- (d)
11.2 cc (STP) of nitrogen and 0.015g of nitric oxide
Two students A and B report the weight of the same substance as 4.0 and 4.00 g respectively. Which of the following statements is correct?
- (a)
Both are equally accurate
- (b)
A is more accurate than B
- (c)
B is more accurate than A
- (d)
Both are inaccurate scientifically
Which of the following statements indicates that law of multiple proportions is being followed?
- (a)
Sample of carbon dioxide taken from any source will always have carbon and oxygen in the ratio 1 : 2
- (b)
Carbon forms two oxides namely CO2 and CO, where masses of oxygen which combine with fixed mass of carbon are in the simple ratio 2 : 1
- (c)
When magnesium burns in oxygen, the amount of magnesium taken for the reaction is equal to the amount of magnesium in magnesium oxide formed
- (d)
At constant temperature and pressure, 200 mL of hydrogen will combine with 100 mL oxygen to produce 200 mL of water vapour
Vapour density of a gas is 11.2. Volume occupied by 2.4 g of this at STP will be
- (a)
2.4 L
- (b)
2.24 L
- (c)
22.4 L
- (d)
11.2 L
0.75 moles of a solid A4 are heated with 2 moles of O2 (g) in a sealed vessel.Completely using up the reactants, the reaction produces only one compound. It is observed that when the temperature is used to that of initial temperature, the contents of the vessel exhibit a pressure equal to 1/2 of the original pressure. The formula for the product will be
- (a)
A2O3
- (b)
A3O8
- (c)
A3O4
- (d)
AO2
A certain amount of a metal whose equivalent mass is 28, displaces 0.7 L of H2 at STP from an acid. The mass of an element would be
- (a)
1.75 g
- (b)
6.875 g
- (c)
3.50 g
- (d)
7.00 g
The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecule is
- (a)
1 : 4
- (b)
7 : 32
- (c)
1 : 8
- (d)
3 : 16
How many moles of magnesium phosphate Mg3(PO4)2 will contain 0.25 mole of oxygen atoms?
- (a)
0.02
- (b)
3.125 x 10-2
- (c)
1.25 x 10-2
- (d)
2.5 x 10-2
If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit. The mass of one mole substance will
- (a)
be a function of molecular mass of the substance
- (b)
remains unchanged
- (c)
increase two fold
- (d)
decreases twice
Number of atoms in 560 g of Fe (atomic mass 56 mol-1) is
- (a)
twice that of 70 g N
- (b)
half that of 20 g H
- (c)
Both (a) and (b)
- (d)
None of the above
In an organic compound of molar mass 108 g mol-1, C, H and N present in 9 : 1 : 3.5 by weight. Molecular formula can be
- (a)
C6H8N2
- (b)
C7H10N
- (c)
C5H6N3
- (d)
C4H18N3