Q. $1g$ of copper powder was taken in a china dish and heated. What change takes place on heating? When hydrogen gas is passed over this heated substance, a visible change is seen in it. Give the chemical equation of reactions, the name and the colour of the products formed in each case.

Q. List the important products of the Chlor-alkali process. Write one important use of each.

Q. How is washing soda prepared from sodium carbonate? Give its chemical equation. State the type of this salt. Name the type of hardness of water that can be removed by it?

Q. $3$ mL of ethanol is taken in a test tube and warmed gently in a water bath. A $5\%$ solution of alkaline potassium permanganate is added first drop by drop to this solution, then in excess.
How is $5\%$ solution of $KMn{O}_4$ prepared?

Q. $3$ mL, of ethanol is taken in a test tube and warmed gently in a water bath. A $5\%$ solution of alkaline potassium permanganate is added first drop by drop to this solution, then in excess.
State the role of alkaline potassium permanganate in this reaction. What happens on adding it in excess?

Q. $3$ mL, of ethanol is taken in a test tube and warmed gently in a water bath. A $5\%$ solution of alkaline potassium permanganate is added first drop by drop to this solution, then in excess.
Write chemical equation of this reaction.

Q. A squirrel is in a scary situation. Its body has to prepare for either fighting or running away. State the immediate changes that take place in its body so that the squirrel is able to either fight or run?

Q. Why is chemical communication better than electric impulses as a means of communication between cells in a multi-cellular organism?

Q. Name a cyclic unsaturated carbon compound.

Q. Define the term pollination. Differentiate between self-pollination and cross-pollination. What is the significance of pollination?

Q. The change in magnetic field lines in a coil is the cause of induced electric current in it. Name the underlying phenomenon.

Q. What are homologous structures? Give an examples. Is it necessary that homologous structures always have a common ancestor. Justify you answer.

Q. Why is Tyndall effect shown by colloidal particles? State four instances of observing the Tyndall effect?

Q. Differentiate between a glass slab and a glass prism. What happens when a narrow beam of (i) a monochromatic light, and (ii) white light passes through (a) glass slab and (b) glass prism?

Q. Draw a labelled diagram to show (i) reddish appearance of the sun at the sunrise or the sunset

Q. Draw a labelled diagram to show (i) white appearance of the sun at noon when it is overhead.

Q. A V-I graph for a nichrome wire is given below. What do you infer from this graph? Draw a labelled circuit diagram to obtain such a graph.
Refer above image.

Q. Write the mathematical expression for Joule's law of heating.

Q. List two common signs of sexual maturation in boys and girls.

Q. Compute the heat generated while transferring $96000$ coulomb of charge in two hours through a potential difference of $40V$.

Q. Carbon cannot reduce the oxides of sodium, magnesium and aluminium to their respective metals. Why? Where are these metals placed in the reactivity series? How are these metals obtained from their ores? Take an example to explain the process of extraction along with chemical equations.

Q. What is the result of reckless female foeticide?

Q. Which contraceptive method changes the hormonal balance of the body?

Q. Write two factors that determine the size of a population.

Q. The position of certain elements in the modern Periodic Table are shown below.

Q. The position of certain elements in the modern Periodic Table are shown below.

Q. The position of certain elements in the modern Periodic Table are shown below.

$\downarrow$ Period /Group $\to$	1	2	3 to 12	13	14	15	16	17	18
1	G								H
2	A			I			B		C
3		D			E				F

Using the above table answer the following questions giving reasons in each case:
Which element is a metal with valency 2?

Q. The position of certain elements in the modern Periodic Table are shown below.

$\downarrow$ Period /Group $\to$	1	2	3 to 12	13	14	15	16	17	18
1	G								H
2	A			I			B		C
3		D			E				F

Q. The position of certain elements in the modern Periodic Table are shown below.

$\downarrow$ Period /Group $\to$	1	2	3 to 12	13	14	15	16	17	18
1	G								H
2	A			I			B		C
3		D			E				F

Using the above table answer the following questions giving reasons in each case:
To which family does H, C and F belong?

Q. Define atomic size. Give its unit of measurement. In the modern Periodic Table what trend is observed in the atomic radius in a group and a period and why is it so?