Heredity and Evolution — Science STD 10 — Question

A potential difference of 100 V is applied across a wire for two minutes. If the current through the wire is 0.1 A, find the heat produced in joule.

What is a nuclear reactor? What is the fuel used in a nuclear reactor?

What is the force on a current-carrying wire that is parallel to a magnetic field? Give reason for your answer.

Why is an electric light bulb not filled with air? Explain why argon or nitrogen is filled in an electric bulb.

Explain the term “rancidity”. What damage is caused by rancidity?

Write any two observations in an activity which may suggest that a chemical reaction has taken place. Give an example in support of your answer.

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 two uses of a compound microscope.

The elements in the second period : Li, Be, B, C, N, O, F and Ne have electrons in the two shells K and L. Write down the electronic configuration of these elements.

Define :Vitamins: