Explanation:
The scientific notation:

where
and k is integer.
We have the example:

You can write the numbers in a "normal" form:

Make the sum:

And next write it in the scientific notation:

<h3>Other method:</h3>
You can add numbers in scientific notation if the power of tens in both number is the same.
Therefore you must convert the first number:

Now, you can make the sum:

Answer:
<h3>The answer is 200 cm³</h3>
Explanation:
The volume of a substance when given the density and mass can be found by using the formula

From the question
mass = 150 g
density = 0.75 g/cm³
We have

We have the final answer as
<h3>200 cm³</h3>
Hope this helps you
Answer:
If you continue to cool water past 4 degrees Celsius, its density starts to plummet (you can see this in the graph). At zero degrees, i.e., the temperature at which water turns into ice, the density of water is actually quite low. It turns out that ice has a lower density than water, and any object that has a lower density than the liquid form on which it’s kept (in this case, water) will be able to float!
Explanation:
Molar volume at STP = 22,4 L
1 mole -------------- 22,4 L
x mole -------------- 11,2 L
x = 11,2 / 22,4
x = 0,5 moles of N2
1 mole --------------- 6,02.10²³ molecules
0,5 moles ------------ y molecules
y = 0,5 . 6,02.10²³
y = 3,01.10²³ molecules