science & technology Online Quiz - 18

A calorimeter is an apparatus used to measure quantities of heat. It quantifies thermal energy transferred during physical or chemical processes.

A dynamo converts mechanical energy into electrical energy through electromagnetic induction. It's essentially a generator that produces electricity when rotated.

A dynamometer measures electric power or mechanical force. It quantifies the power output or torque of engines and motors. Dynamo generates electricity, electrometer measures potential difference.

A fluxmeter is an instrument designed to measure magnetic flux or magnetic field strength. It operates on the principle of electromagnetic induction and is commonly used in physics laboratories and engineering applications.

According to the Big Bang theory, the universe began in an extremely hot and dense state approximately 13.8 billion years ago. As space expanded, the universe cooled, allowing particles to form and eventually creating the conditions for matter and structure to develop.

The age of the universe is approximately 13.75 billion years (13.75 × 10^9 years), based on measurements of the cosmic microwave background radiation and the expansion rate of the universe (Hubble constant). This estimate comes from the Planck satellite mission and other cosmological observations.

The Hubble Space Telescope was originally scheduled for launch in 1986, but the Challenger disaster in January of that year grounded the shuttle fleet for nearly 3 years. Hubble finally launched in April 1990 aboard Discovery. This delay was a direct consequence of the safety stand-down after Challenger.

In 1994, NASA released Hubble Space Telescope images of the Orion Nebula (M42) that provided the first direct visual evidence of protoplanetary disks around young stars. These images, taken with the newly installed corrective optics, showed 'proplyds' - disks of dust and gas where planets are forming. This was a landmark discovery in planetary formation theory.

General relativity describes black holes as regions where spacetime curvature is infinite, but they are not made of pure gravitational energy without matter. Matter collapses into a singularity at the center, retaining its mass, charge, and angular momentum.

The human body contains over 75 kilometers of nerves if all nerve fibers were laid end to end. This includes both the central and peripheral nervous systems. The extensive network allows for complex communication throughout the body.

Nerve impulses travel at speeds between 100-400 km/h, which is slower than Formula 1 cars that can exceed 300 km/h. This makes the statement false. The comparison highlights the remarkable but finite speed of neural communication in the human body.

The human brain contains approximately 100 billion neurons. While each neuron can form thousands of connections (synapses), the exact number varies by region and individual. The statement captures the immense complexity of neural networks in the brain.

The adult human brain typically weighs between 1.3-1.4 kilograms. Saying it weighs 'about 1.5kg' is a reasonable approximation commonly used in general knowledge contexts. The brain accounts for about 2% of body weight despite consuming 20% of the body's energy.

Humans have exceptionally large brains relative to body size compared to other animals. The encephalization quotient (brain size relative to expected size for body mass) is highest among humans. While some animals have larger absolute brain sizes (elephants, whales), humans have the highest brain-to-body mass ratio.

On average, male brains are approximately 10% larger than female brains in absolute volume. This difference primarily correlates with overall body size differences between sexes. Brain size does not determine intelligence or cognitive ability, and male-female brain structure shows more similarities than differences.

Brass (an alloy of copper and zinc) discolours in air due to reaction with hydrogen sulphide, forming a dark layer of copper sulphide on the surface. Oxygen, carbon dioxide, and nitrogen do not cause this discolouration. This is a common chemistry phenomenon observed in brass objects.

Bromine is the only non-metal that exists as a liquid at room temperature (25°C). It has a melting point of -7.2°C and boiling point of 58.8°C. Phosphorous and chlorine are non-metals but are solids and gases respectively at room temperature. Helium is a noble gas.

Chlorophyll is a chelate compound where magnesium is the central metal ion, coordinated to a porphyrin ring. This is similar to heme in blood where iron is the central metal. Copper, iron, and calcium are not the central metal in chlorophyll.

Graphite is used in pencil cores mixed with clay - the material we call pencil 'lead' contains no actual lead. Charcoal is used in charcoal pencils but not standard writing pencils. Silicon and phosphorus have no role in pencil manufacturing.