none of the above. is the answer
Answer:
Subtract them.
Explanation:
''''"Since all number in scientific notation have base 10, we can always multiply them and divide them. To multiply two numbers in scientific notation, multiply their coefficients and add their exponents. To divide two numbers in scientific notation, divide their coefficients and subtract their exponents."""""
I was actually learned about this in school just found an source.
1. 2CaS + 2H2O --> Ca(HS)^2 + Ca(OH)^2
2. Au^2S^3 + 3H2 --> 2Au + 3H2S
