When matter loses heat, one of the following happens:
Liquid changes to solid (freezing), or
Gas changes to liquid (condensation), or
Gas changes to solid (deposition)
1- Freezing: when the temperature of a liquid matter drops below its freezing point, the liquid usually solidifies forming crystals. Example of this is when water changes to ice
2- Condensation: when the temperature of gas is reduced, the molecules slow down and come together changing the matter into liquid. Example of this is when water vapor condenses into water droplets.
3- Deposition: Sometimes when the temperature of a gas drops, it solidifies directly without passing through the liquid phase. An example of this is when water vapor changes directly to ice in sub-freezing areas without passing through the liquid phase. This is the process through which clouds are formed.
The diagram below shows these three changes in matter.
Answer : The final temperature of the metal block is, 
Explanation :

As we know that,

.................(1)
where,
q = heat absorbed or released
= mass of aluminum = 55 g
= mass of water = 0.48 g
= final temperature = ?
= temperature of aluminum = 
= temperature of water = 
= specific heat of aluminum = 
= specific heat of water= 
Now put all the given values in equation (1), we get
![55g\times 0.900J/g^oC\times (T_{final}-25)^oC=-[0.48g\times 4.184J/g^oC\times (T_{final}-25)^oC]](https://tex.z-dn.net/?f=55g%5Ctimes%200.900J%2Fg%5EoC%5Ctimes%20%28T_%7Bfinal%7D-25%29%5EoC%3D-%5B0.48g%5Ctimes%204.184J%2Fg%5EoC%5Ctimes%20%28T_%7Bfinal%7D-25%29%5EoC%5D)

Thus, the final temperature of the metal block is, 
Answer:
Option B is correct.
4
Explanation:
We know that an atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.
All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example, if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.
In given problem we are given with 2 neutrons of helium. We know that the atomic number of He is 2. Thus Mass number of He is,
Number of neutrons + number of proton
2 + 2 = 4
Thus, option B is correct.
Answer:
C. Hair dryer
Explanation:
Alternating Current
The other kind of electricity is called alternating current, or AC. Power plants produce this
type of electricity. It is carried by large power lines from the plant to your home. When you
plug a TV, a lamp, or a hair dryer into the wall socket, you are using this type of electricity.