Answer:
89.7
Explanation:
First we have to look at the right of the digit which is going to be round. If it is 5 or greater than 5 than the number left to it should be increased by one.
For example
In given number 89.667 after three digits 8, 9, 6 the next digit is 6.
So in order to round the number to three digits 6 will rounded to 7 and value becomes 89.7
If the digit next to rounded digit is less than 5 than number will rounded as,
For example:
56.42
Rounded to three digit it will be 56.4.
<span>It can be inferred from atomic line spectra. These are certain wavelengths of light that atoms give off when they become excited. The energy levels in an atom can be proven to exist from this phenomenon, and furthermore, they can be measured.</span>
Answer: 12.0 milliliters of 6.50 M HCl ( aq ) are required to react with 2.55 g Zn.
Explanation:
moles =
moles of zinc =
The balanced chemical equation is :

According to stoichiometry:
1 mole of zinc reacts with = 2 moles of HCl
Thus 0.0390 moles of zinc reacts with =
moles of HCl
To calculate the volume for given molarity, we use the equation:
.....(1)
Molarity of
solution = 6.50 M
Volume of solution = ?
Putting values in equation 1, we get:


Thus 12.0 ml of 6.50 M HCl ( aq ) are required to react with 2.55 g Zn