Explanation: Sulphur is used in the process of vulcanization of rubber. During vulcanization, sulphur forms cross-links between the rubber molecules, improving elasticity, strength, and resistance to heat and wear. This makes natural rubber more durable and suitable for industrial use.

Explanation: In 1643, Italian scientist Evangelista Torricelli invented the barometer, an instrument used to measure atmospheric pressure. His mercury barometer demonstrated that air has weight and that atmospheric pressure can support a column of mercury in a glass tube.

Explanation: A sphygmomanometer is a medical instrument used to measure blood pressure. It consists of an inflatable cuff, a mercury or aneroid gauge, and a bulb for inflation. The cuff is wrapped around the upper arm and inflated to temporarily stop blood flow. As pressure is slowly released, readings are taken for systolic (maximum) and diastolic (minimum) pressure. Normal blood pressure for a healthy adult is about 120/80 mmHg.

Explanation: Acids do not turn red litmus to blue; they turn blue litmus paper red. Acids are sour in taste, corrosive in nature, and have a pH value less than 7. The statement that acids turn red litmus to blue is incorrect.

Explanation: In fused (molten) sodium chloride, electric current passes due to the presence of free ions. When solid NaCl is melted, it dissociates into Na⁺ and Cl⁻ ions, which can move freely and conduct electricity. In the solid state, these ions are fixed in the crystal lattice, so it does not conduct electricity.

Explanation: EDUSAT (Education Satellite) was launched by the Indian Space Research Organisation (ISRO) in September 2004. It was the first Indian satellite built exclusively for educational purposes, designed to provide distance learning and interactive education through satellite communication.

Explanation: The nerve cell or neuron is the longest cell in animals. It consists of a cell body, dendrites, and a long fiber called the axon. In humans, the axon of a motor neuron can be over 1 meter long (from the spinal cord to the toes). This structure helps transmit electrical impulses rapidly across the body, allowing coordination and communication between organs.

Explanation: Dakshin Gangotri is India’s first scientific research station established in Antarctica in 1983–84. It was set up by the Indian Antarctic Programme under the National Centre for Polar and Ocean Research (NCPOR). Located about 2,500 km from the South Pole, it served as a base for scientific studies related to glaciology, meteorology, and environmental sciences. Though it is now buried under ice and functions as a supply base, it marked India’s permanent presence in Antarctica. Later stations include Maitri (1989) and Bharati (2012).