I believe the answer is orbital hybridization theory
Statement D is the correct option as the solution will have pH of 3. It has an H3O+ ion concentration of 1 × 
mol/L and is acidic.
Explanation:
It is given in question that solution must have pH of 3. The value if being less than 7 shows that solution is acidic. The pH value of 3 indicates that given solution is highly acidic and has strong acid. Strong acid gets fully dissociated into 
ions.
pH of the solution is calculated as:
pH = -log10[]
the concentration or molarity of the hydronium ion is given as moles/litre
concentration of hydronium ion in the solution is 1 X moles/litre
putting the values in the equation:
pH = - log10( 1 X )
pH = 3 (acidic)
Thus it can be concluded that D option is the right answer.
Which atom?
Atomic mass - proton
Answer:
D. 15g
Explanation:
The law of conservation of mass states that, in a chemical reaction, mass can neither be created nor destroyed. This means that the amount of matter in the elements of the reactants must be equal to the amount in the resulting products.
In this question, 25 grams of a reactant AB, was broken down in a reaction to produce 10 grams of products A and X grams of product B. According to the law of conservation of mass, the mass of the reactant must be equal to the total mass of the products. This means that 25 grams must also be the total mass of both products in this reaction. Hence, if product A is 10 grams, product B will be 25 grams - 10 grams = 15 grams.
Therefore, product B must be 15 grams in order to form a total of 25 grams when added to the mass of product A. This will equate the mass of the reactant AB and fulfill the law of conservation of mass.
