summer vacation hw class x

1. What happens when dilute hydrochloric acid is added to iron fillings? Tick the
correct answer.
(a) Hydrogen gas and iron chloride are produced.
(b) Chlorine gas and iron hydroxide are produced.
(c) No reaction takes place.
(d) Iron salt and water are produced.
2 . What is a balanced chemical equation? Why should chemical equations be balanced?
3. Translate the following statements into chemical equations and then balance them.
(a) Hydrogen gas combines with nitrogen to form ammonia.
(b) Hydrogen sulphide gas burns in air to give water and sulpur dioxide.
(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium
(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.
4. Balance the following chemical equations.
(a) HNO3 + Ca(OH)2 Ca(NO3)2 + H2O
(b) NaOH + H2SO4 Na2SO4 + H2O
(c) NaCl + AgNO3 AgCl + NaNO3
(d) BaCl2 + H2SO4 BaSO4 + HCl
5. Write the balanced chemical equations for the following reactions.
(a) Calcium hydroxide + Carbon dioxide Calcium carbonate + Water
(b) Zinc + Silver nitrate Zinc nitrate + Silver
(c) Aluminium + Copper chloride Aluminium chloride + Copper
(d) Barium chloride + Potassium sulphate Barium sulphate + Potassium chloride
6. Write the balanced chemical equation for the following and identify the type of reaction in each case.
(a) Potassium bromide(aq) + Barium iodide(aq) Potassium iodide(aq) + Barium bromide(s)
(b) Zinc carbonate(s) Zinc oxide(s) + Carbon dioxide(g)
(c) Hydrogen(g) + Chlorine(g) Hydrogen chloride(g)
(d) Magnesium(s) + Hydrochloric acid(aq) Magnesium chloride(aq) + Hydrogen(g)
7. A piece of wire of resistance R is cut into five equal parts. These parts are then
connected in parallel. If the equivalent resistance of this combination is R, then the
ratio R/Ris –
(a) 1/25 (b) 1/5 (c) 5 (d) 25
8. Which of the following terms does not represent electrical power in a circuit?
(a) I2R (b) IR2 (c) VI (d) V2/R
9. An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be –
(a) 100 W (b) 75 W (c) 50 W (d) 25 W
10. Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then
parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be
– (a) 1:2 (b) 2:1 (c) 1:4 (d) 4:1
11. How is a voltmeter connected in the circuit to measure the potential difference between two points?
12 . A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10–8 m. What will be the length of this wire to make its
resistance 10 ? How much does the resistance change if the diameter is doubled?
13 . The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor
are given below –
I (amperes) 0.5 1.0 2.0 3.0
V (volts) 1.6 3.4 6.7 10.2 13.2
Plot a graph between V and I and calculate the resistance of that resistor.
14 . When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of
the resistance of the resistor.
15. How many 176 resistors (in parallel) are required to carry 5 A on a 220 V line?