Question: 7. What is the chemical name formula of GYPSUM? Write chemical equation for its preparation. 
Answer: Chemical formula of Gypsum is CaSO4. 2H2O.
Equation for its preparation:
CaSO4. 1/2 H2O + 1½H2 → CaSO4. 2H2O
(Plaster of Paris)
Question: 8. Answer the following with respect to excretory system in humans: 
(1). What is the location of kidneys in the body?
(2). What is glomerulus? What role does it play during urine formation?
(3). What is the rate of fluid filtered out in Bowman’s capsule?
Question: 9. A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is:
(1). Pushed into the coil.
(2). withdrawn from the coil.
(3). held stationary near the coil.
Draw diagram to represent each situation and explain the deflection in the galvanometer.
- Pointer of galvanometer is deflected to the right side.
- Pointer of galvanometer is deflected to the left side.
- No deflection of pointer of galvanometer showing current is not induced in this case.
Draw a circuit diagram of an electric circuit containing a cell, a key, an ammeter, a resistor of 4Ω in series with a combination of two resistors (8Ω each) in parallel and a voltmeter across parallel combination. Each of them dissipate maximum energy and can withstand a maximum power of 16w without melting. Find the maximum current that can flow through the resistors.
Question: 10. When electrolysis of water is done then: 
(1). Identify the gases evolved at cathode and anode. (Write equations also)
(2). Why is amount of gas collect in one of the test tubes double the amount in the other? Name this gas.
- At cathode H2 gas; At anode O2 as.
- The volume of H2 gas at cathode is double than volume of O2 gas collected at anode as in H2O molecule, two parts of hydrogen combine with one part of oxygen (by their volume).
Question: 11. Ethanol is used on a large scale at commercial level. This is a very useful chemical. It is commonly called alcohol and is the active ingredient of alcoholic drinks. But consumption of alcohol also causes drunkenness and this practice is socially condemned.
Read the text given and answer the following questions:
(1). Give two chemical properties of ethanol.
(2). As a responsible student of the class, what steps would you take to discourage the use of alcohol?
- (i). It is a colourless liquid at room temperature.
(ii). It has very low melting point (156 K) and low boiling point (351 K or 78°C).
- By sensitising people about harmful effects of liquor consumption, by making posters, banners and writing articles on this issue.