Write balanced chemical equations for each of the following reactions and also classify them.
(a) Lead acetate solution is treated with dilute hydrochloric acid to form lead chloride and acetic acid solution.
(b) A piece of sodium metal is added to absolute ethanol to form sodium ethoxide and hydrogen gas.
(c) Iron (III) oxide on heating with carbon monoxide gas reacts to form solid iron and liberates carbon dioxide gas.
(d) Hydrogen sulphide gas reacts with oxygen gas to form solid sulphur and liquid water.

You are given a hammer, a battery, a bulb, wires and a switch :

(a) How could you use them to distinguish between samples of metals and non-metals?

(b) Assess the usefulness of these tests in distinguishing between metals and non-metals.

Calculate the energy supplied by 100 kW of power in one hour.

Why is it not easy for carbon to take part in the formation of ionic compounds ?

Why planets do not twinkle?

Mention any four water harvesting structures.

An element 'M' has atomic number 12.
(a) Write its electronic configuration.
(b) State the group to which 'M' belongs.
(c) State the group to which 'M' belongs.
(c) Is 'M' a metal or a non-metal?
(d) Write the formula of its oxide.

How do organisms, whether reproduced asexually or sexually maintain a constant chromosome number through several generation? Explain with the help of suitable example.

Name the three products of 'chlor-alkali' process.Write one commercially or industrially important material each that can be prepared from each of these products

State reason for the following:
(i) Non-metals cannot displace hydrogen from the acids.
(ii) Hydrogen is not a metal, yet it is placed in the activity series of metals.
(iii) Aluminium is more reactive than iron, yet its corrosion is less than that of iron

What is 'translocation'? Why is it essential for plants?Where in plants are the following synthesized:
(i)Sugar  (ii)Hormones

Two lamps, one related 60W at 220 W at 220V and the other 40 W at 220 V, are connected in parallel to the electric supply at 220V.
(a) Draw a circuit diagram to show the connections.
(b) Calculate the current drawn from the electric supply.
(c) Calculate the total energy consumed by the two lamps together when they operate for one hour.

A man went door to door posing to be a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument, the man beat a hasty retreat.
(i) Can you play the detective to find out the nature of the solution he had used?
(ii) What is 24 carat gold?

Explain the important of soil for plant growth.

With the help of a labelled circuit diagram illustrate the pattern of field lines of the magnetic field around a current carrying straight long conducting wire. How is the right hand thumb rule useful to find direction of magnetic field associated with a current carrying conductor?

State the reason why carbon can neither form C⁴⁺ cations for C^4- anions, but forms covalent compounds. Also state reasons to explain why covalent compounds:
(a) are bad conductors of electricity?
(b) have low melting and boiling points

(a)Identify A, B and C in the given diagram and write their functions.
(b)Mention the role of gamete and zygote in sexually reproducing organisms.

A student wants to project the image of a candle flame on the walls of school laborated by using a mirror
(a) Which type of mirror should he use and why?
(b) At what distance in terms of focal length 'f' of the mirror should he place the candle flame so as to get the magnified image on the wall?
(c) Draw ray diagram to show the formation of image in this case.
(d) Can he use this mirror to project a diminished image of the candle flame on the same wall? State 'how' if your answer is 'yes' and 'why not' if your answer is 'no'