Answer:
THE NEW VOLUME OF THE GAS IS 406 mL WHEN THE TEMPERATURE CHANGES FROM 765 K TO 315 K.
Explanation:
When the temperature changes from 765 K to 315K, the volume has changed from 986 mL to?
V1 = 986 mL = 0.986 L
T1 = 765 K
T2 = 315 K
V2 = unknown
Using Charles' equation of gas laws;
V1 / T1 = V2 / T2
Making V2 the subject of the formula:
V2 = V1 T2 / T1
V2 = 0.986 * 315 / 765
V2 = 0.406 L
V2 = 406 mL
So therefore, the volume of a gas changes from 986 mL to 406 mL as a result of a change in temperature from 765 K to 315 K.
Answer: 0.8541 grams of HCl will be required.
Explanation: Moles can be calculated by using the formula:
Given mass of 
= 0.610 g
Molar mass of = 78 g/mol
Number of moles of = 0.0078 moles
The reaction between and HCl is a type of neutralization reaction because here acid and base are reacting to form an salt and also releases water.
Chemical equation for the above reaction follows:
By Stoichiometry,
1 mole of reacts with 3 moles of HCl
So, 0.0078 moles of will react with 
= 0.0234 moles
Mass of HCl is calculated by using the mole formula, we get
Molar mass of HCl = 36.5 g/mol
Putting values in the equation, we get
Mass of HCl required will be = 0.8541 grams
C. Electron. It’s a negatively charged particle that orbits around the nucleus. Usually, there are multiple electrons going around the nucleus in different orbitals (the circle around the nucleus in which the electron travels). The mass is much smaller compared to that of a proton or neutron and can be ignored when calculating the mass of an atom.
