Correct Answer: rough black

Explanation:

Black surfaces are good emitters of heat. If the black surface is rough too, the emitting will be better. Shinning surfaces reflect black radiation . So if the black surface is also shining the effectiveness of emitting heat is lessened.

Correct Answer: An electric arc is a visible plasma discharge between two electrodes that is caused by electrical current ionizing gasses in the air Electric arcs occur in nature in the form of lightning

Correct Answer: Saturn

Explanation:

Saturn, the solar system's second largest planet that takes the prize for least dense. It's less dense than water, which has led many people to postulate that it would float.

However, even if it somehow found its way to a body of water large and deep enough to contain it, Saturn would break apart and its rocky core would sink.

Correct Answer: atrial depolarization

Explanation:

The P wave in the ECG represents atrial depolarization, which results in atrial contraction, or atrial systole.

The P wave is a summation wave generated by the depolarization front as it transits the atria.

Correct Answer: Magma is injected into surrounding rock forming an igneous intrusive

Explanation:

Magma is injected into surrounding rock forming an igneous intrusive.

 

Actually it is a plutonic formation in which magma present beneath Earth surface deforms the shape of rocks present above it
 

Correct Answer: Vacuum

Explanation:

Sound waves cannot travel through a Vacuum.

 

A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work in.

Correct Answer: All of the above

Explanation:

We know that most of the metals are goof conductors of electricity and heat. Metals are very strong but they are malleable i.e, they can be bent into a shape. These are shiny when they are cut or polished. 

 

Hence, metals are malleable, conductors and luster. All the above are properties of the metals.

Correct Answer: collide each other

Explanation:

Heat energy can be transferred by three major methods. They are 

 

1. Conduction,

2. Convection and

3. Radiation.

 

Conduction is the movement of heat through a substance by the collision of molecules

Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy.

Radiation is the transfer of energy by means of photons in electromagnetic waves governed by the same laws. It occurs through a vacuum or any transparent medium.

Correct Answer: Sunlight

Explanation:

A resource is a source or supply from which a benefit is produced. Resources can be broadly classified upon their availability they are renewable and non renewable resources.

 

Renewable Resources :: A resource that can be replenished after use are known as Renewable resources.

Examples :: Sunlight, Water, biomass,...

 

Non renewable Resources :: A resource that, once used, is no longer available are known as Non renewable Resources. 

Example :: Coal, fossil fuels, natural gas,...

 

Sunlight is the both renewable and inexpensive resource from the given options.

Correct Answer: Kinetic energy

Explanation:

Every object has two typea of energies. They are ::

Potential energy

Kinetic energy

 

If the object is in motion, then it has Kinetic energy (KE). Potential energy (PE) is energy that is "stored" because of the position and/or arrangement of the object.

 

Hence, another name for energy of motion is called Kinetic energy.