P-1 Chemical reactions and equations — Science STD 10 — Question

Remake the table taking into account relation between entries in three columns.

I	II	III
Coal	Potential energy	Wind electricity plant
Uranium	Kinetic energy	Hydroelectric plant
Water reservoir	Nuclear energy	Thermal plant
Wind	Thermal energy	Nuclear power plant

Explain the following reactions giving their balanced chemical equations: Iron powder is added to copper sulphate solution.

Explain why, the flow of energy in the ecosystem is said to be unidirectional.

State uses of a convex lens.

What is meant by dialysis? What type of patients are put on dialysis?

Some insects are very useful for us. We get many products from them. e.g. Honey bee, Lac insect, Silk worm, are the insects that provide us with honey and wax, lac and silk respectively. The culture experiments are done on these insects for large scale production of these substances. Butterflies help in the pollination of crops and are thus helpful for the farmers and gardeners. Lady bug beetle is an insect which acts as a natural pest control as it attacks the other harmful insect pests.

In biological pest control methods it is widely used. Some insects, on the contrary are very harmful. Mosquito, bed bugs, lice are blood sucking parasites which can spread the diseases. Mosquito is a vector for dengue, filariasis and malaria. Some are biting insects that can cause wounds, some cause allergies of various kinds. The grains and crops are destroyed to great extent by the insects. In this way the insects belonging to the phylum Arthropods are harmful to health, wealth and peace of mind too.

(ii) Which are the animals from phylum Arthropoda those have shortest and longest life span?

State the disadvantages of nuclear energy.

What were the two criteria used by Mendeleev to classify the elements in his periodic table?

Iron is a conductor of electricity, but when we pick up a piece of iron resting on the ground, why don’t we get electric shock?

On going through the modern periodic table it is seen that the elements Li, Be, B, C, N, O, F and Ne belong to the period-2. write down electronic configuration of all or them.