Answer
_2 HNO₃ + 1 Mg(OH)₂ → 1 Mg(NO₃)₂ + 2 H₂O
Explanation
Given:
______HNO3 + Mg(OH)2 ------>
Solution:
Note that the reaction between an acid and a base will give salt and water only.
Hence the complete reaction of the given equation is:
___HNO₃ + Mg(OH)₂ → Mg(NO₃)₂ + H₂O
To get the balanced equation for the acid-base reaction, 2 moles of HNO₃ will react with 1 mole of Mg(OH)₂ to produced 1 mole of Mg(NO₃)₂ and 2 moles of H₂O.
Therefore, the complete and balanced equation for the given acid-base reaction is:
_2 HNO₃ + 1 Mg(OH)₂ → 1 Mg(NO₃)₂ + 2 H₂O
It should remain constant because of the law of conservation of mass and because the flask is sealed no mass will escape
Answer: If you think about it, B. would be the most reasonable answer with the given factors.
Answer: Scientific notation- 
Explanation: I got this by moving the decimal, so that there is one non-zero digit to the left of that decimal point. Tip- The number of decimal places you move will be the exponent on the 10.
Moved right- Negative
Moved left- Positive
Answer: “We live on a hunk of rock and metal that circles a humdrum star that is one of 400 billion other stars that make up the Milky Way Galaxy which is one of billions of other galaxies which make up a universe which may be one of a very large number, perhaps an infinite number, of other universes. That is a perspective on human life and our culture that is well worth pondering.”
― Carl Saga
Is this it mate?