Question 4: C
question 5: D
Answer:
135g Na2CO3
Explanation:
I'm going to assume you mean Molality which is mol solute/kg solvent
Molarity would be mol soute/ L solution
we know we have 155g of water which is .155 kg
essentially we have the equation:
mol/kg = 8.20
we substitute .155 in for kg and get:
mol/.155 = 8.20
Solving this gives mol = 1.271
now we must convert to grams using the molar mass
Molar mass Na2CO3 = 106G/mol
so to cancel moles we multiply:
1.271mol x 106g/mol
= 135g
Answer: A. Cilla Is Correct.
The answer would be 7 because of this solution:
You divide (1|2) and then divide it by 7.
The answer should be 0.78% of the remaining half-lives after 7. Because of the remaining radioactive substance that happens during that 0.78 percentage.
Yes it is for example look at Iodine and Tellurium.
Hope this helps :).