Bacteria thrive in warm, moist conditions. Refrigeration allows the temperature to be lowered so far that food can be stored for days or even months. Keeping food cold (at or below 4°C) slows down bacterial growth which helps reduce the risk of foodborne illness.

Correct Option: B

Bacteria thrive in warm, moist conditions. Refrigeration allows the temperature to be lowered so far that food can be stored for days or even months. Keeping food cold (at or below 4°C) slows down bacterial growth which helps reduce the risk of foodborne illness.

Under-inflated tyres create more friction with the road, increasing fuel consumption by up to ten per cent and are prone to skidding on either wet or slippery surfaces. Low pressures also lead to premature wear and risk of tyre blowout or bulging.

Correct Option: C

Under-inflated tyres create more friction with the road, increasing fuel consumption by up to ten per cent and are prone to skidding on either wet or slippery surfaces. Low pressures also lead to premature wear and risk of tyre blowout or bulging.

The volume of materials changes depending on current temperature. Usually heat makes them expand, and cold leads them to contract. There have to be gaps to avoid strain on the tracks. The same applies in many other fields of engineering, i.e. bridge building.

Correct Option: D

The volume of materials changes depending on current temperature. Usually heat makes them expand, and cold leads them to contract. There have to be gaps to avoid strain on the tracks. The same applies in many other fields of engineering, i.e. bridge building.

A fuse or fusable link works by opening an electrical circuit when the current becomes too high. As the current increases, the temperature of the wire increases. So a fuse wire should have a low melting point and should be connected in series with the appliance. Besides, it should have a comparatively high resistance.

Correct Option: A

A fuse or fusable link works by opening an electrical circuit when the current becomes too high. As the current increases, the temperature of the wire increases. So a fuse wire should have a low melting point and should be connected in series with the appliance. Besides, it should have a comparatively high resistance.

A node is a point along a standing wave where the wave has minimal amplitude. The opposite of a node is an anti-node, a point where the amplitude of the standing wave is a maximum. The distance between a node and anti-node is 1/2 of a wavelength; since a wavelength is from one node to another (or any point to its next “identical” point). So if w is the wavelength, then
1 2
= 30. So, w = 30 × 2 = 60 cm

Correct Option: D

A node is a point along a standing wave where the wave has minimal amplitude. The opposite of a node is an anti-node, a point where the amplitude of the standing wave is a maximum. The distance between a node and anti-node is 1/2 of a wavelength; since a wavelength is from one node to another (or any point to its next “identical” point). So if w is the wavelength, then
1 2
= 30. So, w = 30 × 2 = 60 cm