Answer:
B
Explanation:
This is because exothermic reactions occurs when bnds are formed, and involves the release of energy.
Endothermic reaction occur when bonds are broken,and involves absorption of energy.
When waves act together, you talk about "interference".
When they reinforce each other, it is "constructive interference".
When they cancel each other, it is "destructive interference".
A covalent bond is a form of chemical bonding between two non-metals, whereas ionic bonding is a bond between a metal and a non-metal.
Answer:
The further an electron is from the nucleus. the greater its energy level.
Explanation:
When an electron is close to the nucleus, it is at as low an energy level as it can get.
We must put energy into an electron to pull it away from the attraction of a nucleus.
So, electrons that are further from the nucleus are at higher energy levels.
corrected question: A chemist adds 135mL of a 0.21M zinc nitrate solution to a reaction flask. Calculate the mass in grams of zinc nitrate the chemist has added to the flask. Round your answer to significant digits.
Answer:
5.37g
Explanation:
0.21M means ; 0.21mol/dm³
1dm³=1L , so we can say 0.21mol/L
if 0.21mol of Zinc nitrate is contained in 1L of water
x will be contained in 135mL of water
x= 0.21*135*10³/1
=0.02835moles
number of moles= mass/ molar mass
mass= number of moles *molar mas
molar mass of Zn(NO₃)₂=189.36 g/mol
mass= 0.02835 *189.36
mass=5.37g