General Science Quiz: Physics, Biology, and Health

Pyrex glass is heat-resistant due to its low thermal expansion coefficient, which prevents it from cracking under rapid temperature changes. It contains boron oxide (borosilicate glass) that gives it these properties, making it ideal for laboratory and kitchen use.

Photosynthesis is an endothermic (energy-absorbing) process because it requires energy input from sunlight to convert carbon dioxide and water into glucose and oxygen. The process stores energy in chemical bonds, which is why it's considered endothermic.

Refrigerators produce cooling through the evaporation of a volatile liquid refrigerant. When the refrigerant evaporates in the evaporator coils, it absorbs heat from the refrigerator compartment, creating the cooling effect. This is based on the principle that evaporation requires latent heat.

The brain relies almost exclusively on glucose for its energy requirements, as it cannot use fatty acids or other fuels directly. Under normal conditions, glucose is the primary substrate for brain metabolism, though it can use ketone bodies during fasting.

Blood contains iron (in hemoglobin), copper (in ceruloplasmin), and magnesium (as an electrolyte). Chromium is not a normal constituent of blood and is not required in blood physiology. While trace chromium exists in the body, it's not a blood component like the other elements listed.

The Goldman Environmental Prize (often called Goldman Awards) honors grassroots environmental activists for outstanding contributions to protecting the environment. It's the world's largest prize for grassroots environmental activism, recognizing individuals for sustained and important efforts to protect or enhance the natural environment.

Average speed = distance/time = 350 km/7 hrs = 50 km/hr. However, the question asks for average VELOCITY, which is a vector quantity requiring both magnitude and direction. Since we don't know the exact direction between Bangalore and Chennai, we cannot determine the average velocity. Also, the distance given might not be the straight-line displacement needed for velocity calculation.

Without gravity, a projectile launched at 45° has equal initial horizontal and vertical velocity components (vx = v₀cos45°, vy = v₀sin45°). With no acceleration, both components remain constant and equal, so x = y at all times. This gives x - y = 0 as the equation of the straight-line path in the x-y plane. The motion is linear, not circular, and x + y = 0 would mean x = -y, which is incorrect.

In uniform circular motion, acceleration is centripetal - it always points toward the center of the circular path. This acceleration is responsible for continuously changing the direction of velocity to maintain circular motion, not the tangent (which would be the velocity direction).

In circular motion, linear velocity v equals radius r multiplied by angular velocity w (v = rw). This relationship holds because angular velocity w is defined as the rate of change of angle, and the arc length traveled is r times the angle.

Newton's first law states that an object at rest stays at rest AND an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. A moving body with no net force will continue moving at constant velocity, not come to rest.

Friction is a non-conservative force because the work done against friction depends on the path taken - a longer path means more work is lost to friction. In contrast, conservative forces like gravity and electric force have work done that is independent of the path, depending only on initial and final positions.

After 15 minutes, exactly 3 half-lives have passed (15/5 = 3). Each half-life reduces the amount by half, so after 3 half-lives: 1 gram * (1/2)^3 = 1 * 1/8 = 0.125 gram remains.

AIDS (Acquired Immunodeficiency Syndrome) is indeed classified as a pandemic because it has spread worldwide across multiple continents and affected millions of people. The term pandemic refers to the global spread of a disease, not its severity. AIDS has caused millions of deaths globally since its emergence, making the 'True' option correct.

Both symptoms described are common manifestations of HIV/AIDS. The whitish coating (thrush) is caused by Candida fungal infection, and purple spots (Kaposi's sarcoma) are a type of cancer associated with advanced HIV. These occur because HIV weakens the immune system, making patients susceptible to opportunistic infections. Therefore option C 'Both' is correct.

Acute HIV Syndrome (also called acute retroviral syndrome or seroconversion illness) refers to the flu-like symptoms that occur 2-4 weeks after initial HIV infection, as the virus rapidly replicates and the body develops antibodies. It is NOT when HIV progresses to AIDS (which takes years), nor is it the final fatal stage. This early stage is often mistaken for common viral illnesses like flu or mononucleosis.

Healthcare workers protect themselves through multiple strategies: taking all possible precautions like wearing waterproof gloves and careful needle handling (option C), AND in case of accidental exposure, taking PEP (Post-Exposure Prophylaxis) drugs within 72 hours to prevent infection (option A). They definitely face risk, so option B is false. Therefore option D 'Both a and c' is correct.