Could anyone explain this question to me, because I really don't know how to approach it. I would type it up, but it would take ages!

cheers

## 2004 - Multiple Choice - Q5

### Pammy

Posted 23 May 2006 - 12:48 PM

You just need to find the mass of each of the atoms.

For example the first one, H O tells us there are 2 hydrogen ions, whose mass each is one, therefore the total mass of the hydrogen ion = 2, there is only one oxygen, and the mass number is 16, therefor total mass of atom= 18

IF go go through this for all of them you should get

1. 18

2. 19

3. 20

4. 20

5. 21

6. 22

From this you can see 3 & 4 are the same, which makes the answer

Hope this helps

For example the first one, H O tells us there are 2 hydrogen ions, whose mass each is one, therefore the total mass of the hydrogen ion = 2, there is only one oxygen, and the mass number is 16, therefor total mass of atom= 18

IF go go through this for all of them you should get

1. 18

2. 19

3. 20

4. 20

5. 21

6. 22

From this you can see 3 & 4 are the same, which makes the answer

**D**Hope this helps