important question of chemistry for class 10th board exam
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Q14. Write balanced equations for the following reactions:
i. Chlorine is passed into an aqueous solution of sulphur dioxide.
ii. Aluminium powder is warmed with hot and concentrated caustic soda solution.
iii. Concentrated nitric acid is added to copper turnings kept in a beaker.
iv. Red lead (trilead tetroxide) is warmed with concentrated hydrochloric acid.
v. Chlorine gas is passed through an aqueous solution of iron (II) sulphate
acidified with dilute sulphuric acid.
Q15. Which of the following methods A, B, C, D or E is generally used for preparing the chlorides listed below from (i) to (v). Answer by writing down the chloride and the letter pertaining to the corresponding method. Each letter is to be used only once.
A. Action of an acid on a metal
B. Action of an acid on an oxide or carbonate
C. Direct combination
D. Neutralization of an alkali by an acid
E. Precipitation (double decomposition)
(i) Copper (II) chloride (ii) Iron (II) chloride
(iii) Iron (III) chloride (iv) Lead (II) chloride
Q16. (i) Name the ore of zinc containing its sulphide.
(ii) In the process of extracting zinc, the above named ore is roasted. Write the equation for the reaction which takes place when the sulphide ore is roasted.
(iii) Name the substance used to reduce the roasted ore. Write the equation for the reaction.
i. The moles of sulphur dioxide present in the flask.
ii. The number of molecules of sulphur dioxide present in the flask.
iii. The volume occupied by 3.2g of sulphur dioxide at S.T.P.(S = 32, 0 = 16)
Q17. Aluminium is extracted from its chief ore, Bauxite. The ore is first purified and the metal is extracted from it by electrolytic reduction.
i. Write three balanced equations for the purification of bauxite by Hall’s process.
ii. Name a chemical used for dissolving aluminium oxide. In which state of subdivision is the chemical used?
iii. Write an equation for the reaction which takes place at the anode during the extraction of aluminium by the electrolytic process.
iv. Mention one reason for the use of aluminium in thermite welding.
Q18. (i) Write the equation for the reaction in the Haber process that forms ammonia.
(ii) State the purpose of liquefying the ammonia produced in the process.
(iii) Predict the group of an element X if its atomic number is 16.
(iv) State one reason why tap water is not used to prepare a solution of silver nitrate
Q19. (i) Write the equation for the preparation of ethylene from ethyl alcohol.
(ii) Write the general formula for a saturated hydrocarbon and give one example of a saturated hydrocarbon with its structural formula.
(iii) Name a compound which will give acetylene gas when treated with water.
Q20. Which particular property of cast iron makes it unsuitable for the construction of bridges?
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