Which of the following examples are based upon the total internal reflection of light?
(A) Optical fibre
(B) Twinkling of stars
(C) Mirage
(D) Sparkling of diamond
Choose the correct answer from the options given below:

The force between two electric charges is expressed by the equation : \( F = \frac{kq_1q_2}{r^2} \).
Which of the following is a correct statement ?

The ratio of equivalent capacitance in series and parallel combinations of two capacitors of capacity 5 F and 20 F will be

Arrange the range of frequencies of the following series of hydrogen atom in ascending order
(A) Balmer
(B) Lyman
(C) Paschen
(D) Bracket
Choose the correct answer from the options given below:

An e.m.f. \( e_s = 50 \sin(314t) \) is applied across a pure capacitor of \( 637 \ \mu\text{F} \).
The instantaneous current \( I \) is:

The critical angle of incidence \( i_c \) for a ray incident from a denser to a rarer medium, is that angle for which

A bar magnet is cut into two equal halves along a plane parallel to the magnetic axis. The one parameter which remains unchanged is

A line passes through the point with position vector \(2 \hat{i}-\hat{j}+4 \hat{k}\) and is in the direction of the vector \(\hat{i}+\hat{j}-2 \hat{k}\). The equation of the line in Cartesian form is:

Which of the following will have 46 chromosomes?

Differential coefficient of \(\sec(\tan^{-1} x)\) with respect to x is:

Which one of the following pairs may indicate common ancestry?

Read the following paragraph and answer the given questions:
DRUGS AND ALCOHOL ABUSE
The drugs, commonly abused are opioids, cannabinoids, and coca alkaloids. Opioids are the drugs, which bind to specific opioid receptors present in our central nervous system and gastrointestinal tract. Heroin, commonly called smack is chemically diacetylmorphine which is a white, odourless, bitter crystalline compound. Cannabinoids are a group of chemicals, which interact with cannabinoid receptors present principally in the brain. Natural cannabinoids are obtained from the inflorescences of the plant Cannabis sativa. The flower tops, leaves and the resin of cannabis plant are used in various combinations to produce marijuana, hashish, charas and ganja. Generally taken by inhalation and oral ingestion, these are known for their effects on cardiovascular system of the body. It interferes with the transport of the neuro-transmitter dopamine. Cocaine, commonly called coke or crack is usually snorted. It has a potent stimulating action on central nervous system, producing a sense of euphoria and increased energy. Excessive dosage of cocaine causes hallucinations. Other well-known plants with hallucinogenic properties are Atropa belladona and Datura. These days cannabinoids are also being abused by some sportspersons. Drugs like barbiturates, amphetamines, benzodiazepines, and other similar drugs, that are normally used as medicines to help patients cope with mental illnesses like depression and insomnia, are often abused. Morphine is a very effective sedative and painkiller, and is very useful in patients who have undergone surgery. Several plants, fruits and seeds having hallucinogenic properties have been used for hundreds of years in folk-medicine, religious ceremonies and rituals all over the globe.
__________ are used as medicines to help patients cope with mental illnesses like depression and insomnia.

Which of the following can be classified as broadly utilitarian reason for biodiversity conservation?