Aluminium is the element you are looking for
Answer: E) In a closed system, the total energy always remains constant.
Explanation: For every system, the law of conservation of energy is applicable which states that the energy of the system remains conserved. Energy can neither be created nor destroyed.
A closed system is one which can exchange energy with the surroundings but not mass. Thus if a system absorbs energy, the equivalent amount of energy is lost by surroundings, thus the total energy remains constant.
If a system loses energy, an equivalent amount of energy is gained by surroundings, thus the total energy remains constant.
They look like gases plasmas have no fixed shapes or volume and are less dense tan solids or liquids
5.732 grams of AgCl is formed when 0.200 L of 0.200 M AGNO3 reacts with an excess of CaCl2.
Explanation:
The balanced equation:
2 AgNO3(aq) + CaCl2(aq) -----> 2 AgCl(s) + Ca(NO3)2(aq)
data given:
volume of AgNO3 = 0.2 L
molarity of AgNO3 = 0.200 M
atomic weight of AgCl= 143.32 gram/mole
from the formula, number of moles can be calculated
Molarity = 
number of moles of AgNO3 = 0.04
From the reaction:
2 moles of AgNO3 reacts to form 2 moles of AgCl
0.04 moles of AgNO3 reacts to form x mole of AgCl
= 
= 0.04 moles of AgCl is formed
mass of AgCl formed is calculated by multiplying number of moles with atomic mass of AgCl
mass of AgCl = 0.04 x 143.32
= 5.732 grams of AgCl is formed.
I looked on google cuz i was a lil stumped myself, and it looks like the answer is a. I couldnt find how to solve the equations, sorry