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.
Answer:

Explanation:
The given reactions are:
PbCl2(aq)⇌Pb2+(aq)+2Cl−(aq) 
AgCl(aq)⇌Ag+(aq)+Cl−(aq) 
Required reaction is:
PbCl2(aq)+2Ag+(aq)⇌2AgCl(aq)+Pb2+(aq)

Answer:
Biochemistry.
Explanation:
Biochemistry can be defined as the branch of science that deals with the study of the chemical processes, physio-chemical reactions and various substances that are found in living organisms such as animals, plants, and microorganisms.
Simply stated, biochemistry is a field in science that combines both the elements of biology and chemistry in order to study living organisms.
For example, all living organisms have the ability to engage in respiration in other to breathe in oxygen to stay alive. Thus, biochemistry helps us to understand respiration as a physio-chemical process that converts glucose into a form of energy (Adenosine Triphosphate-ATP) that is beneficial to all living organisms.
Hence, the chemistry of living things and living systems created a new combined field in science known as biochemistry.
Answer:
B is correct → since temperature can be measured confidently and the variations with temperature are greater ( then the errors in measuring time diminishes)
Explanation:
A is not correct → since the sugar cubes will be still surrounded by water at the temperature chosen regardless of the size of the glass, organising the data by size of the glass is not correct since the glass size does not affect in a significant way to the results ( it could affect the cooling rate of water due to the exposed surface , it but would be insignificant)
C is not correct → since the sugar cubes are approximately of the same size , putting 2 cubes or "n" cubes will not affect the time significantly since each cube is still surrounded by water at the same temperature and behaves independently from others , then each cube dissolves at the same time ( there would be small variations due to the different sizes of the cubes and the small variation due to the limited mass of water)
D is not correct → since the solubility of sugar in water is high , the amount left after the experiment would be very small ( thus the relative errors are high) and the sugar would be contaminated with water in the weighting operation, leading to more errors
B is correct → since temperature can be measured confidently and the variations with temperature are greater ( then the errors in measuring time diminishes)