General Science Quiz

Silicon is a semiconductor, meaning its electrical conductivity can be controlled through doping. This property makes it ideal for microprocessor manufacturing. Superconductors offer zero resistance, while non-conductors don't conduct at all.

The four fundamental forces of nature govern all interactions in the universe. The strong nuclear force holds atomic nuclei together, while the weak force is responsible for radioactive decay. Gravity acts on mass across cosmic distances, and electromagnetism mediates interactions between charged particles.

Tritium is a radioactive isotope of hydrogen with one proton and two neutrons, making it hydrogen-3. It is used in glow-in-the-dark watch faces and as a tracer in scientific experiments. The other options are elements that have their own distinct isotopes but tritium specifically refers to hydrogen.

O+ blood can be donated to any Rh-positive recipient (A+, B+, AB+, O+) because it lacks A and B antigens but has the Rh factor. It cannot be given to Rh-negative recipients as they would react to the Rh protein. The Rh+ factor means O+ can only go to other positive blood types.

Alpha decay occurs when a nucleus ejects a helium nucleus (2 protons and 2 neutrons) to become more stable. Beta decay involves electron or positron emission, while gamma decay releases only energy as electromagnetic radiation. The ejected helium particle is specifically called an alpha particle.

Dolphins and sharks both evolved streamlined bodies and fins for efficient swimming despite being mammals and fish respectively. Convergent evolution occurs when unrelated species develop similar traits due to similar environmental pressures, not because of shared ancestry. Other pairs listed share recent common ancestors.

A mole is defined as the amount of substance containing exactly 6.022 x 10^23 elementary entities (atoms, molecules, ions, etc.). This number is called Avogadro's number and serves as a bridge between the atomic scale and macroscopic measurements. It allows chemists to count particles by weighing them.

When measured from the vertical, 0 degrees means the projectile is launched straight up. This gives maximum vertical height since all initial velocity is in the vertical direction. At 90 degrees from vertical (i.e., horizontal), the projectile has no vertical component and achieves zero height.

Assuming a uniform Earth density (ideal case), gravitational force inside the Earth is proportional to distance from center, exactly like a spring's restoring force. The coin accelerates toward the center, reaches maximum speed there, then decelerates, and returns - executing simple harmonic motion. Realistically, Earth's non-uniform density makes it approximately SHM.

Chalcanthite is a hydrated copper sulfate mineral (CuSO4·5H2O). Its name comes from Greek 'chalkos' (copper) and 'anthos' (flower). It forms bright blue crystals and is an important ore of copper. The color is distinctive due to the copper ions.

Sulphuric acid (H2SO4) is industrially prepared by the contact process, where oleum (fuming sulphuric acid, H2S2O7) is an intermediate product. Oleum is then diluted with water to produce concentrated sulphuric acid. This process allows for efficient production of high-purity sulphuric acid at industrial scale.

The maximum horizontal range of a projectile is achieved when it is launched at 45 degrees from the horizontal (or 45 degrees from the vertical). At this angle, the sine and cosine components of the initial velocity are equal, optimizing the product sin(2θ) in the range equation R = (v²sin(2θ))/g. This gives the theoretical maximum range in projectile motion.

Using the kinematic equation v² = u² + 2as, where initial velocity u = 10 m/s (downward), acceleration a = g = 10 m/s², and displacement s = 40 m. This gives v² = 100 + 2(10)(40) = 900, so v = 30 m/s. Options A and B incorrectly ignore initial velocity or miscalculate, while C is physically meaningless.

Angstrom (Å) is a unit of length equal to 10⁻¹⁰ meters, commonly used to measure atomic and molecular distances, wavelengths of light, and sizes of microscopic structures. It is not used for weight, mass, or time.

When a ball rotates in a horizontal circle, it has centripetal acceleration directed toward the center, provided by string tension. When the string breaks, this centripetal force vanishes. According to Newton's first law, the object continues in its current velocity direction - the tangent to the circle at the point of release. It does not fly radially outward (a common misconception), as that would require a force in that direction.

First convert speed: 90 km/hr = 25 m/s. Using v² = u² + 2as, the car stops when 0 = 625 - 8s, so total stopping distance = 78.125 m in 6.25 seconds. Time to stop: v = u + at gives 0 = 25 - 4t, so t = 6.25 s. Since the car stops before the 8th second begins, it covers zero distance during that second.