List of top Science Questions

Assertion (A): Red light signals are used to stop the vehicles on the road.
Reason (R): Red coloured light is scattered the most so as to be visible from a large distance.

Select from the following a plant hormone which promotes cell division.

The phenomena of light involved in the formation of a rainbow in the sky are

In an experiment to study independent inheritance of two separate traits: shape and colour of seeds, the ratio of the different combinations in F₂ progeny would be

A cross between two tall pea plants resulted in offspring having a few dwarf plants. The gene-combination of the parental plants must be

Part(s) of a flower which attracts insects for pollination is (are)

Which of the following statement (s) is (are) true about human heart?
(a) Right atrium receives oxygenated blood from lungs through pulmonary artery.
(b) Left atrium transfers oxygenated blood to left ventricle which sends it to various parts of the body.
(c) Right atrium receives deoxygenated blood from different parts of the body through vena cava.
(d) Left atrium transfers oxygenated blood to aorta which sends it to different parts of the body.

Which one of the following hydrocarbons is different from the others?

Select a pair of natural indicator from the following :

A chemical compound used in glass, soap and paper industries is

The structural formula of Cyclohexane is

Consider the following Chemical equation: a Al₂O₃ + b HCl → c AlCl₃ + d H₂O
In order to balance this chemical equation, the values of a, b, c and d must be

Which one of the following reactions is different from the remaining three?

Identify the product ‘X’ obtained in the following chemical reaction:

What is dispersion of white light ? State its cause. Draw a diagram to show dispersion of a beam of white light by a glass prism.

Draw the diagram of an open stomatal pore and label (I) Guard cells, and (II) Chloroplast on it. Mention two functions performed by stomata.

Design an experiment to demonstrate that carbon dioxide is essential for photosynthesis. Write the observation and conclusion of the experiment.

In the experimental set-up shown above in diagram (I) atmospheric air is being passed into lime water with a syringe while in diagram (II) air is being exhaled into lime water. The time taken for the lime water to turn milky in both the test tubes is different. Give reason.

What is the mass ratio of the gases collected at the anode and cathode?

Differentiate between food chain and food web. In a food chain consisting of deer, grass and tiger, if the population of deer decreases, what will happen to the population of organisms belonging to the first and third trophic levels?

Name the ore of mercury and state the form in which it is found in nature. Write the chemical equations along with the condition required for the reactions involved in the extraction of mercury from its ore.

Name a plant growth hormone synthesized at the shoot tip. Explain its effect on the growth of a plant in response to light.

Write the formula and the molecular mass of the third homologue of alcohols. State how the boiling point of an alcohol changes as one moves from lower to higher homologues.

“The linear magnification produced by a spherical mirror is +3.”Based on this statement answer the following questions:
(a) What is the type of mirror?
(b) Where is the object located?
(c) List two properties of the image formed (other than the size/magnification).

Why is the electrolysis of water called a decomposition reaction?