Answer:It is because acid and water react violently exothermically, producing heat and occasionally melting the fluid.
Explanation:
Answer:- A.
and 
Explanations:- In general, 
In acid-base reaction the acid gives hydrogen ion and the base gives hydroxide ion and these ions combine to form water. Rest of the ions from acid and base combine to form the salt.
Nitric acid breaks to give hydrogen ion and nitrate ion. Similarly, NaOH breaks to give sodium ion and hydroxide ion. Since, hydrogen ion and hydroxide ions form water, the sodium ion and nitrate ion forms the salt, sodium nitrate.
The reaction is shown as:

So, the right choice is A.
Answer:
0.136g
Explanation:
A student dissolved 5.00 g of Co(NO3)2 in enough water to make 100. mL of stock solution. He took 4.00 mL of the stock solution and then diluted it with water to give 275. mL of a final solution. How many grams of NO3- ion are there in the final solution?

Initial mole of Co(NO3)2 

Mole of Co(NO3)2 in final solution

Mole of NO3- in final solution = 2 x Mole of Co(NO3)2

Mass of NO3- in final solution is mole x Molar mass of NO3

Answer:
1.667L of a 0.30M BaCl₂ solution
Explanation:
<em>Of a 0.30M barium chloride, contains 500.0mmol of barium chloride.</em>
<em />
Molarity is an unit of concentration used in chemistry defined as the moles of solute present in 1 liter of solution.
In a 0.30M BaCl₂ solution there are 0.30 moles of BaCl₂ in 1 liter of solution.
Now, in your solution you have 500mmol of BaCl₂ = 0.500 moles of BaCl₂ (1000 mmol = 1 mol). Thus, 0.500 moles of BaCl₂ are present in:
0.500 moles * (1L / 0.30 moles) =
<h3>1.667L of a 0.30M BaCl₂ solution</h3>