B is correct
salt lowers the freezing point of water (colligative property) by lowering the interaction and intermolecular forces between water molecules
D is the answer since it is changing the element.
Answer:
It emits energy since to move from a higher energy level to a lower energy level or ground state, it must lose energy.
In one mole of C7H18 there are 18 moles of H (the number folowing the H)*
>> the ratio is 1:18
In 5.2 moles of C7H18 there are x moles of H
>> the ratio is 5.2:x
Cross multiply the two ratios
1x = 18×5.2
x = 93.6 moles of H
>> In 5.2 moles of C7H18 there are 93.6 moles of H
* This isnt a rule that you can always use.
However to find the mole of a certain element in a certain molucle all you have to do is count how many moles of the element are present in the molecule.
>> example1 >> H2O ;
2 H and 1 O
>> example2 >> CH3COOH ; [you add up all the moles of the same element]
(1+1) 2 C , (3+1) 4 H and (1+1) 2 O
>> example3 >> Mg(OH)2 ; [you multiply whetever is in parenthesis by the number after it 2] 1 Mg , (1×2) 2 O and (1×2) 2 H
