Use blue litmus paper. This is an indicator that can safely determine whether it is a base or an acid by changing color in response to the substance. This color indicates whether it is an acid or a base. Refer to the pH scale to see if the substance is basic or acidic.
Na: +1 (sodium)
S: -2 (sulfur)
=> Na2S
If I were you, I'd try to go with this one :
![[(6)(-241.8)+(5)(-393.5)]-[-35.1] =-481.6](https://tex.z-dn.net/?f=%20%5B%286%29%28-241.8%29%2B%285%29%28-393.5%29%5D-%5B-35.1%5D%20%3D-481.6)
. I think that is a solution you have to find. Just use the sum of standard enthalpies of products and <span>of reactants. Hope you will find it helpful!</span>
Humans have selectively bred plants and animals for thousands of years including: crop plants with better yields.