Sources of Energy — Science STD 10 — Question

A, B and C are three living organisms. The organism A is a unicellullar fungus which can live without air. It is used in the commercial production of an organic compound P from molasses. The organism B is a unicellular animal which lives in water and feeds and moves by using pseudopodia. It breathes through an organelle Q. The organism C is a tiny animal which acts as a carrier of malarial parasite. It breathes and respires through a kind of tiny holes R and air - tubes S in its body.

1. What are organisms A, B and C?
2. Name P, Q, R and S.
3. Which organism/ organisms undergo aerobic respiration?
4. Which organism/ organisms undergo anaerobic respiration?

A black metal oxide XO is used as a catalyst in the preparation of oxygen gas from potassium chlorate. The oxide XO is also used in ordinary dry cells. The metal oxide XO cannot be reduced satisfactorily with carbon to form metal X.

1. Name the metal X.
2. Name the metal oxide XO.
3. Which reducing agent can be used to reduce XO to obtain metal X?
4. Name another metal which can also be extracted by the reduction of its oxide with the above reducing agent.

What is long-sightedness? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show:

1. The eye-defect long-sightedness.
2. Correction of long-sightedness by using a lens.

State and explain the reaction, if any, of the following metals with a solution of copper sulphate:

1. Gold.
2. Copper.
3. Zinc.
4. Mercury.

Define atomic size. Give its unit of measurement. In the modem periodic table what trend is observed in the atomic radius in a group and a period and why is it so?

What are the disadvantages of using nuclear power?

When metal X is treated with a dilute acid Y, then a gas Z is evolved which burns readily by making a little explosion.

1. Name any two metals which can behave like metal X.
2. Name any two acids which can behave like acid Y.
3. Name the gas Z.
4. Is the gas Z lighter than or heavier than air?
5. Is the reaction between metal X and dilute acid Y, exothermic or endothermic?
6. By taking a specific example of metal X and dilute acid Y, write a balanced chemical equation for the reaction which takes place. Also indicate physical states of all the reactants and products.

1. What is a solenoid? Draw a sketch of the pattern of field lines of the magnetic field through and around a current carrying solenoid.
2. Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right hand rule to find out the direction of the magnetic field inside and outside the loop.