<h2>IM SORRY I CAN'T UNDERSTAND YOUR QUESTION PLEASE TRY AGAIN PLEASE DONT REPORTED MY ANSWER THIS IS FOR MY FAMILY MY SARV AND SELEVER</h2>
Answer:
a. 10.0 g
Explanation:
The molar mass of NaOH is 39.997 grams which was calculated by adding the molar mass of Sodium, Oxygen, and Hydrogen 
. But before we do anything with this number we must first convert 
molecules to moles. We can do this by dividing by Avogadro's number or 
( 
moles). We then convert moles to grams by multiplying by the molar mass of NaOH, (
grams). This is almost exactly 10 and the margin of error is likely due to the original numbers not being precise enough.
The correct reference for this isotope is A. Oxygen-18.
B,speedof light>speed of sound
Answer:
We need 420 cal of heat
Explanation:
Step 1: Data given
Mass of the aluminium = 200.0 grams
Temperature rises with 10.0 °C
Specific heat of aluminium = 0.21 cal/g°C
Step 2: Calculate the amount of heat required
Q =m * c* ΔT
⇒with Q = the amount of heat required= TO BE DETERMINED
⇒with m = the mass of aluminium = 200.0 grams
⇒with c = the specific heat of aluminium = 0.21 cal/g°C
⇒with ΔT = the change of temperature = 10.0°C
Q = 200.0 grams * 0.21 cal/g°C * 10.0 °C
Q = 420 cal
We need 420 cal of heat (option 2 is correct)
