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The biggest source of energy on Earth’s surface is (A) Biomass (B) Solar radiations (C) Tides (D) Winds

(B) Solar radiations Sun (solar radiation) is the biggest source of energy on Earth’s surface. It is also known as the ultimate source of... View Article

Which one of the following statements is not true about nuclear energy generation in a nuclear reactor? 1 (A) Energy is obtained by a process called nuclear fission. (B) The nucleus of Uranium is bombarded with high energy neutrons. (C) A chain reaction is set in the process. (D) In this process a tremendous amount of energy is released at a controlled rate.

(B) The nucleus of Uranium is bombarded with high energy neutrons. The nucleus of Uranium is bombarded with low-energy neutrons, not with... View Article

Fleming’s Right-hand rule gives (A) magnitude of the induced current. (B) magnitude of the magnetic field. (C) direction of the induced current. (D) both, direction and magnitude of the induced current.

(C) direction of the induced current. Fleming's right-hand rule gives us the direction of the induced current when a conductor moves in a... View Article

The resistance of a resistor is reduced to half of its initial value. In doing so, if other parameters of the circuit remain unchanged, the heating effects in the resistor will become (A) two times. (B) half. (C) one-fourth. (D) four times.

(A) two times. We know that, the resistance is given as: V=IR where V = voltage, I = current, and R = Resistance. According to the... View Article

If a person has five resistors each of value 1/5 Ω, then the maximum resistance he can obtain by connecting them is (A) 1 Ω (B) 5 Ω (C) 10 Ω (D) 25 Ω

a) 1Ω We know that total resistance decreases when resistors are connected in parallel. It is calculated as 1/RT = 1/R1 + 1/R2 + 1/R3 +... View Article

Fertilisation is the process of (A) transfer of male gamete to female gamete. (B) fusion of nuclei of male and female gamete. (C) adhesion of male and female reproductive organs. (D) the formation of gametes by a reproductive organ.

B) fusion of nuclei of male and female gamete. Fertilization is the process of fusion of nuclei of male and female gamete to form a diploid... View Article

Most of the digestion and absorption of the food takes place in the (A) small intestine. (B) liver. (C) stomach. (D) large intestine.

b) Small intestine The primary function of the small intestine is the absorption of nutrients and minerals which are found in food.Small... View Article

Anaerobic process (A) takes place in yeast during fermentation. (B) takes place in the presence of oxygen. (C) produces only energy in the muscles of human beings. (D) produces ethanol, oxygen and energy.

(A) takes place in yeast during fermentation The anaerobic process takes place in yeast during fermentation. It takes place in the absence of... View Article

Which one of the following statements is correct about the human circulatory system? (A) Blood transports only oxygen and not carbon dioxide. (B) Human heart has five chambers. (C) Valves ensure that the blood does not flow backwards. (D) Both oxygen-rich and oxygen-deficient blood gets mixed in the heart.

C) Valves ensure that the blood does not flow backward. In the human circulatory system, the human heart consists of four chambers. Both... View Article

Do you think microbes will work similarly in landfill sites as they work in the laboratory? Justify your answer.

The activity of microbes in landfill sites depends upon the research study carried out in the laboratory and the optimization process of waste... View Article

If we discontinue the use of plastic, how can an environment-friendly substitute be provided?

There are lot of environmental friendly substitute are available. These are- Stainless steel, Bamboo, Silicone, Glass, Wood, Jute, Pottery and... View Article

Name any two uses of ‘‘single-use plastic’’ in daily life.

Plastic is a miracle material.Plastic is a lightweight, hygienic and resistant material which can be moulded in a variety of ways and utilized in... View Article

State two methods of effective plastic waste collection in your school.

The methods of effective plastic waste collection in school are reusing the plastic containers by making flower pots and use them as decoration... View Article

Isotopes are (i) Atoms of an element with similar chemical properties but different atomic masses. (ii) Atoms of different elements with similar chemical properties but different atomic masses. (iii) Atoms of an element with different chemical properties but same atomic masses. (iv) Atoms of different elements with different chemical properties but same atomic masses.

b) Atoms of same elements, having the same atomic number but different mass numbers. Isotopes of an element possess the similar number of... View Article

If the letter ‘R’ was used to represent any of the elements in the group, then the hydride and oxide of carbon would respectively be represented as (i) RH4 , RO (ii) RH4 , RO2 (iii) RH2 , RO2 (iv) RH2 , RO

(ii) RH4, RO2 If the letter 'R' was used to represent any of the elements in the group then it will be represented as RH4, RO2. Dmitri... View Article

Why did Mendeleev leave some gaps in the Periodic table?

In 1869, Mendeleev’s a Russian chemist proposed a tabular diagram of known elements. At that time only 63 elements were known. He arranges the... View Article

Write the number of valence electrons present in a nitrogen atom 14_7( N )

The number of valence electrons present in a nitrogen atom (14N7) is 5 (Electronic configuration: 2,5) The electronic configuration of nitrogen... View Article

Rishi went to a palmist to show his palm. The palmist used a special lens for this purpose. (i) State the nature of the lens and reason for its use. (ii) Where should the palmist place/hold the lens so as to have a real and magnified image of an object? (iii) If the focal length of this lens is 10 cm and the lens is held at a distance of 5 cm from the palm, use lens formula to find the position and size of the image.

(i) The nature of the lens will be convex lens and the reason for its use is, it gives a magnified image of the lines on the palm. (ii) The... View Article

Neha visited a dentist in his clinic. She observed that the dentist was holding an instrument fitted with a mirror. State the nature of this mirror and reason for its use in the instrument used by dentist.

The nature of this mirror is concave mirror and the reason for its use in the instrument used by dentist is to obtain an erect and magnified... View Article

A security mirror used in a big showroom has radius of curvature 5 m. If a customer is standing at a distance of 20 m from the cash counter, find the position, nature and size of the image formed in the security mirror.

Object distance, u = −20m Radius of curvature, R = +5 m Then, focal length, f = 5/2 = +2.5 m (∵f=R2) To find: The position, nature, (v) and... View Article

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