Some Basic Concepts of Chemistry

1.0 g of magnesium is burnt with 0.56 g O2 in a closed vessel. Which reactant is left in excess and how much ? (At. wt. Mg = 24, O = 16)

1. Mg, 0.16 g
2. O2, 0.16 g
3. Mg, 0.44 g
4. O2, 0.28 g

6.02 1020 molecules of urea are present in 100 mL of its solution. The concentration of solution is

1. 0.001 M
2. 0.1 M
3. 0.02 M
4. 0.01 M

How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2.0 M HNO3? The concentrated acid is 70\% HNO3.

1. 70.0 g conc. HNO3
2. 54.0 g conc. HNO3
3. 45.0 g conc. HNO3
4. 90.0 g conc. HNO3

In an experiment it showed that 10 mL of 0.05 M solution of chloride required 10 mL of 0.1 M solution of AgNO3, which of the following will be the formula of the chloride (X stands for the symbol of the element other than chlorine)

1. X2Cl2
2. XCl2
3. XCl4
4. X2Cl

Which has the maximum number of molecules among the following ?

1. 44 g CO2
2. 48 g O3
3. 8 g H2
4. 64 g SO2

The number of atoms in 0.1 mol of a triatomic gas is ( NA = 6.02 1023 mol-1)

1. 6.026 1022
2. 1.806 1023
3. 3.600 1023
4. 1.800 1022

25.3 g of sodium carbonate, Na2CO3 is dissolved in enough water to make 250 mL of solution. If sodium carbonate dissociates completely, molar concentration of sodium ion, Na+ and carbonate ions, CO32- are respectively (Molar mass of Na2CO3 = 106 g mol-1)

1. 0.955 M and 1.910 M
2. 1.910 M and 0.955 M
3. 1.90 M and 1.910 M
4. 0.477 M and 0.477 M

10 g of hydrogen and 64 g of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be

1. 3 mol
2. 4 mol
3. 1 mol
4. 2 mol

What volume of oxygen gas (O2) measured at 0 C and 1 atm, is needed to burn completely 1 L of propane gas (C3H8) measured under the same conditions?

1. 5 L
2. 10 L
3. 7 L
4. 6 L

How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCl?

1. 0.011
2. 0.029
3. 0.044
4. 0.333