The volume of oxygen liberated at STP from 15 mL of 20 volume H2O2 is
100 mL
200 mL
300 mL
400 mL
Calculate the molality of a solution that contains 51.2 g of naphthalene (C10H8) in 500 mL of carbon tetrachloride. The density of CCl4 is 1.60 g/mL
0.250 m
0.500 m
0.750 m
0.840 m
When 2.46 gm of a hydrated salt (MSO4xH2O) is completely dehydrated, 1.20 gm of anhydrous salt is obtained. If the molecular weight of anhydrous salt is 120 gm mol-1, what is the value of x?
2
7
4
6
An organic compound contains 90% carbon and 10% hydrogen by mass. Its empirical formula is
C2H4
C3H6
C3H8
C3H4
How many molecules of CO2 are formed when one milligram of 100% pure CaCO3 is treated with excess hydrochloric acid?
6.023 × 1023
6.023 × 1018
6.023 × 1021
6.023 × 1022
5.0 g of sodium hydroxide (molar mass 40 g mol-1) is dissolved in little quantity of water and the solution is diluted upto 100 ml. What is the molarity of the resulting solution?
0.1 mol dm-3
1.0 mol dm-3
0.125 mol dm-3
1.25 dm-3
0.02 mole of [Co(NH3)5Br]Cl2 and 0.02 mole of [Co(NH3)5Cl]SO4 are present in 200 cc of a solution X. The number of moles of the precipitates Y and Z that are formed when the solution X is treated with excess barium chloride are respectively.
0.02, 0.02
0.01, 0.02
0.02, 0.04
0.04, 0.02
A 100% pure sample of a divalent metal carbonate weighing 2 g on complete thermal decomposition releases 448 cc of carbon dioxide at STP. The equivalent mass of the metal is
40
20
28
12
B.
20
Let the metal be M, so the formula of its carbonate is MCO3.
Molar mass of MCO3 = x + 12 + 3 × 16
= (x + 60) g/ mol
(Let atomic mass of M be x)
448 cc (448 mL) CO2 is produced from carbonate = 2gm.
22400cc CO2 will be obtained from carbonate
= = 100 gm
100 = x + 60
x = 100 - 60 = 40 g/mol
Eq. wt. of metal = = 20 g equiv-1
Molar heat capacity of aluminium is 25 JK-1 mol-1. The heat necessary to raise the temperature of 54 g of aluminium (atomic mass 27 g mol-1) from 30°C to 50°C is
1.5 kJ
0.5 kJ
1.0 kJ
2.5 kJ