English Medium कक्षा १० - CBSE Important Questions for Science

In a food chain of frog, grass, insect and snake, assign trophic level to frog.

In the following food chain, only 2J of energy was available to the peacocks. How much energy would have been present in Grass? Justify your answer.

GRASS → GRASS HOPPER → FROG → SNAKE → PEACOCK

Study the given figure of a Food web and identify the primary consumer in the food web:

If a harmful chemical enters a food chain comprising peacocks, plants, rats and snakes, which of these organisms is likely to have the highest concentration of the chemical in its body? Justify your answer. Name the process involved and define it.

What is an oxidising agent?

\[\ce{Fe2O3 + 2Al -> Al2O3 + 2Fe}\]

The above reaction is an example of a ______.

Translate the following statement into a chemical equation and then balance it.

Hydrogen sulphide gas burns in the air to give water and sulphur dioxide.

Translate the following statement into a chemical equation and then balance it.

Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.

Write the balanced chemical equation for the following reaction.

\[\ce{Aluminium + Copper chloride -> Aluminium chloride + Copper}\]

Write the balanced chemical equation for the following reaction.

\[\ce{Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water}\]

Write the balanced chemical equation for the following and identify the type of reaction. 

\[\ce{Potassium bromide (aq) + Barium iodide (aq) -> Potassium iodide (aq) + Barium bromide (s)}\]

What do you mean by a precipitation reaction? Explain giving an example.

On what basis is a chemical equation balanced?

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.

What is meant by a decomposition reaction?

Identify the substances that are oxidised and the substances that are reduced in the following reaction.

\[\ce{CuO_{(s)} + H2_{(g)} -> Cu_{(s)} + H2O_{(l)}}\]

Complete the following equation:
CH₄ + O₂ —>

Complete the following equation:

CH₂ + H₅OH `("Hot Conc." H_2SO_4)/`>

Complete the following equation:

CH₃COOH + NaOH → 

A student weighed some raisins and recorded the weight as ‘x’. She then soaked the raisins in distilled water. After about 2 hours she removed the raisins, wiped them dry and weighed them again, and recorded that as ‘y’. The percentage of water absorbed by raisins may be determined using the relationship.