In India, the most widely used form of renewable energy is Solar Energy. Due to the country’s tropical location, India receives abundant sunlight throughout the year, making solar power a highly viable and sustainable energy source. It is harnessed using solar panels for electricity generation and heating applications under initiatives like National Solar Mission.

• Geothermal energy: Used only in limited pilot projects.
• Hydro-electric energy: Important but not as rapidly expanding as solar.
• Thermal energy: Usually refers to non-renewable coal-based power plants.

Explanation: PARAM 8000 is India's first supercomputer, developed in 1991 by the Centre for Development of Advanced Computing (C-DAC) under the leadership of Dr. Vijay Bhatkar. It marked India’s entry into high-performance computing and was capable of 1 GigaFLOP (one billion calculations per second).

The highest tides, known as spring tides, occur during the time of the new moon and the full moon. During these phases, the Sun, Moon, and Earth are aligned in a straight line, causing their combined gravitational forces to produce higher high tides and lower low tides. This alignment amplifies the tidal effect, resulting in the strongest tidal ranges.

Other options (for context)

• Solar eclipse: Can coincide with a new moon but is not directly responsible for higher tides.
• Lunar eclipse: Occurs during a full moon but does not always produce exceptionally high tides.
• Volcanoes: Have no relation to tidal movements; tides are caused by gravitational forces, not geological activity.

Explanation: Marijuana is a psychoactive drug obtained from the female inflorescence (flowering tops) of the Cannabis sativa plant. It contains the active compound tetrahydrocannabinol (THC), which affects the central nervous system and alters mood and perception.

Explanation: Respiration is a biochemical process in which food molecules (mainly glucose) are oxidized to release energy in the form of ATP (adenosine triphosphate). This energy is then used for various life processes such as movement, growth, repair, and maintenance. Respiration occurs in all living cells and takes place mainly inside the mitochondria.

Chemical Equation:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP)

In contrast, photosynthesis stores energy in glucose molecules, while respiration releases that stored energy for cellular use.

Explanation: When a man inside a moving train tosses a coin and it falls behind him, it means the train is moving forward with acceleration. The coin, after being tossed, continues to move with the train’s initial velocity, but since the train speeds up, the coin appears to fall backward relative to the man.

Explanation: The sour taste of a lemon is due to the presence of citric acid. Citric acid is a weak organic acid found naturally in citrus fruits such as lemons, oranges, and limes. It gives them their characteristic tangy flavor and also acts as a natural preservative.

Explanation: The intensity and magnitude of an earthquake are measured using a scientific instrument called a seismograph. It records the vibrations or seismic waves produced by earthquakes. The data obtained from a seismograph are used to calculate the earthquake’s strength on scales such as the Richter Scale or the Moment Magnitude Scale. The seismogram (the recorded graph) shows the amplitude and duration of the waves, helping scientists locate the earthquake’s epicenter and determine its severity.

The electron was discovered by J. J. Thomson in 1897 during his experiments with cathode rays. He demonstrated that cathode rays are composed of tiny negatively charged particles, which he named electrons. This discovery revolutionized atomic theory and led to the development of the plum pudding model of the atom, where electrons are embedded in a positively charged sphere.

Other options (for context)

• Enrico Fermi: Known for his work on nuclear physics and the development of the first nuclear reactor.
• Robert Noyce: Co-inventor of the integrated circuit (microchip).
• James Dyson: Inventor of the modern vacuum cleaner, not a physicist.

Explanation: Dissolved oxygen (DO) is the amount of oxygen available in water for aquatic organisms to breathe. For the healthy survival of most aquatic life, the DO level should be between 4 and 6 mg/L. Levels below 3 mg/L can lead to stress or suffocation, especially for fish and aerobic microorganisms. Higher DO levels are typical of clean, cold, and well-aerated waters, while polluted or stagnant waters often have lower oxygen levels due to organic decay.

Factors Affecting DO Levels:

• Temperature (higher temperature = lower DO)
• Organic pollution and bacterial activity
• Photosynthesis by aquatic plants and algae
• Water turbulence and aeration