List of top Science Questions

To balance the chemical equation, the values of the coefficients x, y, z, and t must be: Zn(NO₃)₂ → ZnO + NO₂ + O₂

Assertion (A): Some vegetable oils are healthy. Reason (R): Vegetable oils generally have long unsaturated carbon chains.

Assertion (A): Green plants trap only 1% of the energy of sunlight that falls on their leaves. Reason (R): All green plants are the producers in a food chain.

Carbon compounds :
(i) are good conductors of electricity.
(ii) are bad conductors of electricity.
(iii) have strong forces of attraction between their molecules.
(iv) have weak forces of attraction between their molecules.
The correct statements are :

The oxide which can react with HCl as well as KOH to give corresponding salt and water is

Select from the following the conditions responsible for the rapid spread of black mould on a slice of bread: (i) Formation of large number of spores (ii) Presence of moisture and nutrients in bread (iii) Low temperature (iv) Presence of hyphae

The current carrying device which produces a magnetic field similar to that of a bar magnet is:

Assertion (A): Sex of the children will be determined by what they inherit from their mother. Reason (R): Women have XX sex chromosomes.

Assertion (A): Myopic eye cannot see distant objects distinctly.
Reason (R): For the correction of myopia converging lenses of appropriate power are prescribed by eye-surgeons.

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

Solid Calcium oxide reacts vigorously with water to form Calcium hydroxide accompanied by the liberation of heat. From the information given above it may be concluded that this reaction

Select out of the following a gland which does NOT occur as a pair in the human body:

Which of the following is a redox reaction, but not a combination reaction?

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 through vena cava from upper and lower body.
(d) Left atrium transfers oxygenated blood to aorta which sends it to different parts of the body.

Study the I-V graph for three resistors of resistances R₁, R₂ and R₃ and select the correct statement from the following:

Consider the following compounds:
FeSO₄ ; CuSO₄ ; CaSO₄ ; Na₂CO₃
The compound having the maximum number of water of crystallisation in its crystalline form in one molecule is:

The maximum resistance of a network of five identical resistors of $\frac{1}{5}$ $\Omega$ each can be –

At what distance from a convex lens should an object be placed to get an image of the same size as that of the object on a screen ?

A metal and a non-metal that exists in liquid state at the room temperature are respectively :

When 2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as:

Identify the food chain in which the organisms of the second trophic level are missing :

Assertion (A): The rate of breathing in aquatic organisms is much faster than in terrestrial organisms.
Reason (R) :The amount of oxygen dissolved in water is very high as compared to the amount of oxygen in air.

Assertion (A): Electrons move from lower potential to higher potential in a conductor. Reason (R): A dry cell maintains electric potential difference across the ends of a conductor.

In case of four wires of same material, the resistance will be minimum if the diameter and length of the wire respectively are

Name and explain the phenomenon of light due to which the path of a beam of light becomes visible when it enters a smoke filled room through a small hole. Also state the dependence of colour of the light we receive on the size of the particle of the medium through which the beam of light passes.