Section: Exposition
Each question carries 1 mark:
1. F ill in the blanks:
(a) The chemical name of baking soda is _________.
(b) Sodium carbonate decahydrate is the chemical name of ____________
(c) The compound CuSO4.5H2O is called ______________
(d) Hydrated copper sulphate contains five molecules of ________ of crystallization.
(e) The common name of calcium oxy chloride is _________
2. M atch the important chemicals given in column A with the chemical name and formulae given
in column B.
Column A Column B
(a) Plaster of Paris (i) CaSO4.2H2O
(b) Bleaching powder (ii) Na2CO3. 10 H2O
(c) Washing soda (iii)CaSO4. 1/2 H2O
(d) Baking soda (iv) CaOCl2
(e) Gypsum (v) NaHCO3
3. WHO AM I
(a) I am an important constituent of baking powder. If I am not present, the cake will taste
bitter. Identify me and give my molecular formula
(b) I am an important compound of calcium. I am used for sterilizing drinking water and
also used as an oxidising agent in chemical industries. Give my chemical name and
molecular formula.
(c) If I am not present in cement, it will set hard very fast. What is my common name and
molecular formula?
(d) I am a compound of sodium and I am used in glass industry and for softening hard
water. Give my common name and chemical name.
(e) I am a compound of sodium and I am used in fire extinguishers. I am also an important
antacid .What is my common name and chemical name?
(f) I am a chemical substance that gives pink colour in basic medium and remains colourless in acidic medium. What am I?
(g) I am used in hospitals by orthopaedic doctors and I am also used for decoration purpose. Identify and give my molecular formula.
(h) I am evolved when metal carbonate are made to react with dilute acids. Which gas am I?
Each question carries 2 marks:
4. Complete the following table:
S.No Name of hydrated salt Formula Colour
1 Blue vitriol
2 Green vitriol
3. Epsom salt
4. Washing soda
4. Gypsum
5. Plaster of paris
Each question carries 3 marks:
5. While constructing a house, a builder selects marble flooring and marble table tops for the kitchen where vinegar and juices of lemon, tamarind etc. are more often used for cooking. Will you agree to this selection and why?
Each question carries 1 mark:
6. Complete the following reactions:
(a) NaCl +H2O →
(b) Ca(OH)2 + Cl2 →
(c) NaCl + H2O + CO2 + NH3 →
(d) 2 NaHCO3 → heat →
(e) CaSO4.1/2 H2O +11/2 H2O →
Each question carries 2 marks:
7.Write chemical equation for the following industrial preparation, mention two important properties and use of the compound prepared
(a)
(b)
(c)
8. Write the names and chemical formula of the products formed by the:
(a) Action of chlorine on slaked lime
(b) Heating gypsum at 373 K
Each question carries 3 marks:
9. Crystals of copper sulphate are heated in a test tube for some time.
(a) What is the colour of copper sulphate crystals before heating, and after heating?
(a) What is the source of liquid droplets seen on the inner upper side of the test tube during the heating process?
Section: Interpretation & Reasoning
Each question carries 1 mark:
10. A gas is produced when conc. H2SO4 is added to solid sodium chloride taken in a test tube. The gas coming out through the delivery tube is passed over a dry blue litmus paper and then over a moist blue litmus paper. What would you observe? Explain the reason with the help of a chemical equation.
Each question carries 2 marks:
11. A compound ‘X’ of sodium is commonly used in kitchen for making crispy pakoras. It is also used for curing acidity in the stomach. Identify ‘X’. What is its chemical formula? State the reaction which takes place when it is heated during cooking.
12. A substance X, which is an oxide of a metal, is used intensively in the cement industry This element is present in bones also. On treatment with water it forms a solution which turns red litmus blue. Identify X and also write the equation for its chemical reactions with water
13.In one of the industrial processes used for manufacture of sodium hydroxide, a gas ‘X’ is formed as a by-product. The gas ‘X’ reacts with dry slaked lime to give a compound ‘Y’ which is used as a bleaching agent in one chemical industry. Identify X and Y.
Each question carries 3 marks:
14. Salt ‘A’ commonly used in bakery products on heating gets converted into another salt ‘B’ which itself is used for removal of hardness of water and a gas ‘C’ is evolved. The gas ‘C’ when passed through lime water turns it milky. Identify A, B and C.
15. A white powder ‘A’ is a mild non corrosive base and is used in the preparation of cakes. When the powder is heated it gives another powder ‘B’. The powder ‘B’ is recrystallised to get a substance ’C’ which has detergent properties. Identify A, B and C and also write balanced chemical equations for the conversions of ‘A’ to ‘B’.
16. Identify the compound of calcium which is a yellowish white powder and is used for disinfecting drinking water. How is it manufactured? Write the chemical equation for the reaction involved. What happens when it is left exposed to air?
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