On the first one it is supposed to be 18. when you have a +1 charge you subtract it once. how i got 18 tho was from the protons. there was 19 so i subtracted that with 1 and got 18. hope that helped! :)
btw i’m not the best at explaining, i’m sorry :/
Answer:
N2H4 + 2H2O2 ---->N2 + 4H2O
Explanation:
N=2 N=2
H=6 ->8 H=2 ->8
O=2 -> 4 O=1 -> 4
Add coefficients to hydrogen peroxide on the left and water on the right, so that there is an equal number of hydrogens and oxygens.
Answer : The density of an object is, 
Solution : Given,
Mass of an object = 60 g
Volume of an object = 
Formula used :
Now put all the given values in this formula, we get the density of an object.
Therefore, the density of an object is,
Answer:
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