Carbon and its Compounds — Science STD 10 — Question

In the circuit diagram given below, the current flowing across 5 ohm resistor is 1 amp. Find the current flowing through the other two resistors.

In the nuclear reactor of a power plant:

1. How do control rods control the rate of fission?
2. How is heat removed from the reactor core, and what use is made of this heat?

An element X from group 2 of the periodic table reacts with an element Y from group 17 to form a compound.

1. What is the nature of the compound formed?
2. State whether the compound formed will conduct electricity or not.
3. Give the formula of the compound formed.
4. What is the valency of element X?
5. How many electrons are there in the outermost shell of an atom of element Y?

State and explain the Clock face rule for determining the polarities of a circular wire carrying current.

A bright object 50mm high stands on the axis of a concave mirror of focal length 100mm and at a distance of 300mm from the concave mirror. How big will the image be?

How is charcoal prepared? Explain why, charcoal is a better fuel than wood.

Two elements X and Y have atomic numbers 12 and 16 respectively. Write the electronic configuration for these elements. To which period of the Modern Periodic Table do these two elements belong? What type of bond will be formed between them and why?

Give the position, size and nature of image formed by a concave lens when the object is placed:

1. Anywhere between optical centre and infinity.
2. At infinit.

Out of bacteria, spider, fish and chimpanzee, which organism has a better body design in evolutionary terms? Give reason for your answer.

A converging lens of focal length 5cm is placed at a distance of 20cm from a screen. How far from the lens should an object be placed so as to form its real image on the screen?