English Medium Class 10 - CBSE Question Bank Solutions for Science

In the food chain given below, if the amount of energy available at fourth trophic level is 5 kJ, what was the energy available at the producer level?
Grass → Grasshopper → Frog → Snake → Hawk
(a) 500 kJ
(b) 50 kJ
(c) 5000 kJ
(d) 5 kJ

Which of the following limits the number of trophic levels in a food chain?
(a) insufficient food supply from producer level
(b) decrease in energy at higher trophic levels
(c) increase in the number of organisms at higher trophic levels
(d) accumulation of harmful chemicals at higher trophic levels

What percentage of sun's energy falling on the leaves of green plants is utilised by the plants in the process of photosynthesis and stored as chemical energy of food?
(a) 99 per cent
(b) 10 per cent
(c) 1 per cent
(d) 20 per cent

State whether the following statement is true or false:
A chemical equation can be balanced easily by altering the formula of a reactant or product.

What is wrong with the following chemical equation?

Mg   +   O   →   MgO

Correct and balance it.

What does the symbol (aq) represent in a chemical equation?

Which of the following gets the minimum energy through the food chain in an ecosystem?
(a) carnivore
(b) large carnivore
(c) producer
(d) herbivore

A food chain comprises of cat, seed-eating bird, plants, and dog. The organism which will have the maximum concentration of harmful pesticides coming through the food chain is most likely to be :
(a) cat
(b) plants
(c) dog
(d) seed-eating bird

An aquatic food chain comprises of the organisms like tadpoles, weeds, fish and water beetles. The organism which gets the minimum energy through this food chain is :
(a) water beetles
(b) tadpoles
(c) weeds
(d) fish

Most of the water surface of a lake is covered with algae. This algae is part of the food chain which also includes small fish, bird, larvae and big fish. Which of the following will obtain the maximum energy?
(a) big fish
(b) bird
(c) larvae
(d) small fish

If the energy available at the producer level in a food chain is 150 J, how much energy will be transferred to : tertiary consumer?
(a) 15 J
(b) 10 J
(c) 1.50 J
(d) 0.15 J

How will you indicate a solution made in water in a chemical equation?

How will you indicate Exothermic reaction in a chemical equation?

How will you indicate Endothermic reaction in a chemical equation?

In addition to wheat plants, a crop field ecosystem has organisms such as snake, peacock, eagle and mice. If the wheat plants are sprayed with pesticides periodically, which of the following will have the minimum concentration of pesticides in the body?
(a) snake
(b) eagle
(c) mice
(d) peacock

Translate the following statement into chemical equation and then balance the equation:

Phosphorus burns in oxygen to give phosphorus pentoxide.

Translate the following statement into chemical equation and then balance the equation:

Carbon disulphide burns in air to give carbon dioxide and sulphur dioxide.

The ten per cent law is associated with
(a) transfer of energy from various trophic levels to decomposers in a food chain
(b) transfer of ATP energy into muscular energy
(c) transfer of chemical energy from one organism to another
(d) transfer of sun's energy to the organisms called producers.

Translate the following statement into chemical equation and then balance the equation:

Aluminium metal replaces iron from ferric oxide, Fe₂O₃, giving aluminium oxide and iron.

The harmful chemical which is accumulating in human beings through food chain is :
(a) benzenehexachloride
(b) dichlorodiphenyltrichloroethane
(c) chlorofluorocarbon
(d) abscisic acid