Sample Paper – 2013
Class – X
Subject –CHEMISTRY
TIME : 1 HOUR 30 MINUTES M.M.80
SECTION – A (40 MARKS)
(All questions in this section are compulsory)
Q.1
(a) Mr. Ramu wants to electroplate his key chain with nickel to prevent rusting. For this electroplating
(i)Name the electrolyte used (5)
(ii)Name the cathode
(iii)Name the anode
(iv)Give the reaction at the cathode
(v)Give the reaction at anode
(b) Name the following (5)
(i)a metal which is liquid at room temperature
(ii)The process of heating an ore to a high temperature in the presence of air
(iii)The compound formed by the reaction between calcium oxide and silica
(iv)A compound which is added to lower the fusion temperature of the electrolytic bath in the
extraction of aluminium
(v)Name an allotrope of a non metal that allows electricity to pass through it
(c) A – Sodium carbonate, B – Sodium hydrogen carbonate, C – Zinc carbonate (5)
(i) Choose the salt for the following observations from A, B and C
(1) A carbonate which on heating decomposes to form water and carbon di oxide
(2) A carbonate which decomposes on heating to give carbon di oxide only
(3) A carbonate which does not decompose on heating
(ii) Write balanced chemical equations for the following
(1)Action of dilute nitric acid on sodium hydrogen carbonate
(2)Action of dilute hydrochloric acid on zinc carbonate
(d) Three colourless gases P, Q and R can reduce copper (ii) oxide to copper metal (5)
(i) In case of P the products of reaction are copper metal and water, identify gas P
(ii) In case of Q the products are copper metal and carbon di oxide, identify gas Q and write a
balanced chemical equation of reaction of Q with copper (ii) oxide
(iii)In case of R the products of reaction are copper metal, water and nitrogen gas, identify gas R and
write a balanced chemical equation of reaction of R with copper (ii) oxide
(e) Ammonia gas is oxidized in the presence of catalyst as under : (5)
2NH3 + 5/2 O2 → 2NO + 3H2O
(i)If 1.5 grams of NO is formed, what mass of steam is formed
(ii)What volume of oxygen is required at STP to form 10 moles of products
(iii) Define the term vapour density
(f) Give the equations for the following conversions A to E (5)
A B
ZnSO4 → ZnCO3 → Zn(NO3)2
↖ E D ↓C
ZnO ← Zn(OH)2
(g)Salts A, B, C, D and E undergo reactions (i) to (v) respectively. Identify the anion present in these salts
on the basis of these reactions. (5)
(i) When silver nitrate solution is added to a solution of A, a white precipitate, insoluble in dilute nitric
acid is formed
(ii)Addition of dilute hydrochloric acid to B produces a gas which turns lead acetate paper black
(iii)When a freshly prepared solution of ferrous sulphate is added to a solution of C and concentrated
sulphuric acid is gently poured from the side of the test tube, a brown ring is formed
(iv)When dilute sulphuric acid is added to D, a gas is produced which turns acidified potassium
dichromate solution from orange to green
(v) Addition of dilute hydrochloric acid to E produces an effervescence. The gas produced turns lime
water milky but does not affect acidified potassium dichromate solution
(h)
(i) Differentiate ionic and covalent compounds on the basis of (i) rate of reaction (ii) ionization in
solution and (iii) dissociation (3)
(ii)An element has 2 electrons in its M shell. State its position in periodic table and the name assigned
to this group (2)
SECTION – B (40 MARKS)
(Attempt any four questions from this section)
Q.2 (a) Why during prevention of rusting of iron galvanization is preferred to tinning? (2)
(b) Name the process used for concentration of bauxite ore and briefly describe it and also write the
balanced chemical equations related to it (1 + 2 + 2)
(c) Can nitric acid be stored in aluminium containers? Why or why not? (1 + 2)
Q.3 (a) 1 gram of a mixture of a mixture of sodium chloride and sodium nitrate is dissolved in water. On
adding silver nitrate solution, 1.435 grams of silver chloride is precipitated . Calculate the
percentage of sodium chloride in the mixture (3)
AgNO3 + NaCl → AgCl + NaNO3
(Ag = 108, Na = 23, N = 14, O = 16, Cl = 35.5)
(b) Determine the formula of an organic compound if its molecule contains 12 atom of carbon. The
percentage compositions of hydrogen and oxygen are 6.48 and 51.42 respectively (3)
( C = 12, H = 1 and O = 16)
(c) Determine the number of molecules in a drop of water which weighs 0.09 grams (4)
Q.4 (a) Why vanadium pentoxide is used as a catalyst for the preparation of sulphuric acid? (2)
(b) Give two reasons why during laboratory preparation of nitric acid , the temperature should not
exceed 200⁰C (2)
(c) State two properties of ammonia as demonstrated by fountain experiment (2)
(d)Why funnel arrangement is used for the preparation of hydrochloric acid? (2)
(e)Why do metals like iron cobalt and nickel become passive when treated with pure concentrated
nitric acid and how this passivity can be removed? (2)
Q.5 (a)An element has an atomic number 15. State (i) the period to which it belong? (ii) the number of
valence electrons and (iii) whether it is a metal or non metal (3)
(b) How does chemical reactivity of elements changes as one moves from left to right in a period of
modern periodic table? (2)
(c) Why fluorine has higher electronegativity than chlorine? (2)
(d)Why some elements are radioactive by nature? (2)
(e) Define electron affinity (1)
Q.6 (a) Give the structures of ammonium and hydroxyl ions (3)
(b) Why during electrolysis, a low current for longer duration should be used? (2)
(c) Why sodium metal is kept under kerosene oil? (2)
(d)Write three differences between roasting and calcination (3)
Q.7 (a) Write three differences between drying and dehydrating agents (3)
(b) During Haber’s process, how is ammonia separated from unreacted nitrogen and hydrogen (2)
(c) Write a short note on thermite welding with balanced chemical equation (3)
(d) Why ships are made of alloys of aluminium? (2)
Paper Submitted By:
NameShahid khan
Phone No.07860730649
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