Explanation:
As the Earth moves around the sun during a year, the northern half of the Earth is tilted towards the sun in the summer, making daytime longer than night. In winter, this reverses; the earth tilts away from the sun and nighttime becomes longer
Answer:
There are 
grams contained in all the seawater in the world.
Explanation:
At first let is determinate the total mass of seawater (
), measured in grams, in the world by definition of density and considering that mass is distributed uniformly:
Where:
- Density of seawater, measured in grams per liters.
- Volume of seawater, measured in liters.
If 
and 
, then:
The total mass of sodium chloride is determined by the following ratio:
Given that and 
, the total mass of sodium chloride in all the seawater in the world is:
There are grams contained in all the seawater in the world.
Answer:
The mechanical properties of urea formaldehyde resins may be improved by incorporating therein polyvinyl alcohol. The polyvinyl alcohol may be incorporated during pre-mixing, mid mixing, and/or post mixing of the resin components. Resins prepared using polyvinyl alcohol are particularly desirable in articles requiring improved mechanical strength and water resistance, as compared to similar resins prepared without the polyvinyl alcohol such as shingles.
I believe it is b. you only want to change one thing at a time so you know which one thing caused the effect
