List of practice Questions

A 0.24 g sample of compound of oxygen and boron was found by analysis to contain 0.096 g of boron and 0.144 g of oxygen. Calculate the percentage composition of the compound by weight.
Addition of HBr to propene yields 2-bromopropane, while in the presence of benzoyl peroxide, the same reaction yields 1-bromopropane. Explain and give mechanism.

AD is an altitude of an isosceles triangle ABC in which AB = AC. Show that 

(i) AD bisects BC 

(ii) AD bisects ∠A.

When 3.0g of carbon is burnt in 8.00g oxygen, 11.00g of carbon dioxide is produced. What mass of carbon dioxide will be formed when 3.00g of carbon is burnt in 50.0g of oxygen? Which law of chemical combination will govern your answer?

The ionization constant of acetic acid is 1.74 × 10–5. Calculate the degree of dissociation of acetic acid in its 0.05 M solution. Calculate the concentration of acetate ion in the solution and its pH.
Name A,B,C,D,E and F in the following diagram showing change in its state
Name A,B,C,D,E and F in the following diagram showing change in its state
Write down the products of ozonolysis of 1,2-dimethylbenzene (o-xylene). How does the result support Kekulé structure for benzene?
It has been found that the pH of a 0.01M solution of an organic acid is 4.15
What are polyatomic ions? Give examples.
The following table gives the lifetimes of 400 neon lamps: 

Length (in hours) 

Number of lamps 

300 − 400     

14

400 − 500

56

500 − 600

60

600 − 700

86

700 − 800

74

 800 − 900

62

900 − 1000

48


(i) Represent the given information with the help of a histogram. 
(ii) How many lamps have a lifetime of more than 700 hours?

Write the chemical formulae of the following.
(a)Magnesium chloride
(b)Calcium oxide
(c)Copper nitrate
(d)Aluminium chloride
(e)Calcium carbonate

Two sides AB and BC and median AM of one triangle ABC are respectively equal to sides PQ and QR and median PN of ∆ PQR (see Fig. 7.40). Show that: 

(i) ∆ BM≅∆ PQN 

(ii) ∆ ABC≅∆ PQR

Two sides AB and BC and median AM of one triangle ABC

Give the names of the elements present in the following compounds.
(a) Quick lime
(b) Hydrogen bromide
(c) Baking powder
(d) Potassium sulphate.

Which separation techniques will you apply for the separation of the following?

(a) Sodium chloride from its solution in water
(b) Ammonium chloride from a mixture containing sodium chloride and ammonium chloride
(c) Small pieces of metal in the engine oil of a car
(d) Different pigments from an extract of flower petals
(e) Butter from curd
(f) Oil from water
(g) Tea leaves from tea
(h) Iron pins from sand
(i) Wheat grains from husk
(j) Fine mud particles suspended in water

Calculate the molar mass of the following substances.
(a) Ethyne, \(C_2H_2\)
(b) Sulphur molecule, \(S_8\)
(c) Phosphorus molecule, \(P_4\) (Atomic mass of phosphorus= 31)
(d) Hydrochloric acid, \(HCl\)
(e) Nitric acid, \(NO_3\)
BE and CF are two equal altitudes of a triangle ABC. Using RHS congruence rule, prove that the triangle ABC is isosceles.
Compare the properties of electrons, protons and neutrons.
Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.
What are the limitations of J.J. Thomson’s model of the atom?
ABC is an isosceles triangle with AB=AC. Draw AP⊥BC to show that ∠B = ∠C.

Pragya tested the solubility of three different substances at different temperatures and collected the data as given below (results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution).

Substance Dissolved

Temperature in K

283

293

313

333

353

 

Solubility

Potassium nitrate213262106167
Sodium chloride3636363737
Potassium chloride 3535404654
Ammonium chloride2437415566

 

(a) What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 grams of water at 313 K? 
(b) Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain. 
(c) Find the solubility of each salt at 293 K. Which salt has the highest solubility at this temperature? 
(d) What is the effect of change of temperature on the solubility of a salt?

What are the limitations of Rutherford’s model of the atom?
Explain the following giving examples.
(a) Saturated solution
(b) Pure substance
(c) Colloid
(d) Suspension
Describe Bohr’s model of the atom.
Classify each of the following as a homogeneous or heterogeneous mixture.
soda water, wood, air, soil, vinegar, filtered tea.