A physical change is classified as a change that does not affect the identity of the substance. Otherwise, that would be a chemical change. From the picture above, you will know that it is a chemical change if the colored circles combined with a different color. You will know if it's a physical change if there is only separation of the same colors. The answers are shown in the picture attached.
The mass of Ca(CN)2 : 92,11 g/mol
<h3>Further explanation</h3>
Given
0.0321 moles of Ca(CN)2
Required
The mass
Solution
The mole is the number of particles contained in a substance
1 mol = 6.02.10²³
Moles can also be determined from the amount of substance mass and its molar mass
mol(n) = mass(m) : MW(molecular weight)
Input the value :
mass = mol x MW Ca (CN)2
mass = 0.0321 x 92,11 g/mol
mass = 2.957 g
<u>Answer:</u> Oxidation state of Arsenic in the given compound is +3 and that of oxygen is -2.
<u>Explanation:</u>
We are given a compound having formula 
and we need to find the oxidation state of all the atoms in this compound. There are 2 different atoms present in this : Arsenic and Oxygen
Oxidation state is the number which is assigned to an element in a compound which represents the number of electrons lost or gained by an atom in a compound.
Oxidation state of oxygen as -2 which is same always. Now, to calculate the oxidation state of Arsenic, we take the oxidation state of it be 'x'
As, there are two arsenic atoms and three oxygen atoms, then:
Hence, oxidation state of Arsenic in the given compound is +3 and that of oxygen is -2.
