[ Question Bank ] - 2022 — Science STD 10 — Question

Can the following groups of elements be classified as Dobereiner's triads?

1. Na, Si, Cl.
2. Be, Mg, Ca.

Give reason for your answer.

(Atomic masses: Be 9; Na 23; Mg 24; Si 28; Cl 35. 5; Ca 40)

Write a short note.
Moon missions

Write the names and symbols of two very reactive metals belonging to group 1 of the periodic table. Explain by drawing electronic structure, how either one of the two metals reacts with a halogen. With which name is the bond formed between these elements known and what is the class of the compound so formed known? State any four physical properties of such compounds.

ATP: Energy Currency

The surface of water in a lake appears green due to a layer of tiny free-floating organisms X on its surface. The lake water also contains organisms like water beetle, fish and tadpole. The sun shines over the lake water and provides energy for the functioning of this lake ecosystem.

1. What could organisms X be?
2. Write a food chain comprising of all the four organisms mentioned.
3. What is the general name of the food chains like the one written above?
4. Name (i) secondary consumer (ii) producer (iii) tertiary consumer, and (iv) primary consumer, in the above food chain.
5. If the tertiary consumer gets 0.2 J of energy from the secondary consumer, then how much energy was radiated by the sun to the producer?

Answer the question:
What is meant by satellite launch vehicles? Explain a satellite launch vehicle developed by ISRO with the help of a schematic diagram.

What is electromagnetic induction? Who discovered it?

There are five animals P, Q, R, S and T. The animal P always lives in water and has gills for breathing. The animal Q can stay in water as well as on land and can breathe both, through moist skin and lungs. The animal R lives in soil and breathes only through its skin. The animal S lives on land and breathes through spiracles and tracheae. And animal T lives in water and breathes through its cell membrane.

1. Which of the animals could be Amoeba?
2. Which of the animals could be frog?
3. Which animal could be fish?
4. Which animal could be grasshopper?
5. Which animal could be earthworm?

When an object made of metal A is kept in air for a considerable time, it loses its shine and becomes almost black due to the formation of a layer of substance B. When an object made of another metal C is kept in damp air for a considerable time, it gets covered with a green layer of substance D. Metal A is the best conductor of electricity whereas metal C is the next best conductor of electricity.

1. What is metal A?
2. What is metal C?
3. Name the substance B.
4. Name the substance D.
5. What type of chemical can be used to remove the green layer from metal C and clean it? Why?