Answer:
One mole of U238 ( 6.022 X 10^23 atoms) is 238 grams; one mole of U235 is 235 grams. The difference in molecular weight between a mole of U235 and U238 is 3 grams, the secret to enriching uranium.
Explanation:
Answer:
The Earth rotates on its axis at a constant tilt.
Earths rotation on its axis at a constant tilt provides seasonal changes in the different part of the country. This resulted to the distribution of the heat of the sun from northern hemisphere and to southern hemisphere. Making areas with hot temperature may experience rainy season in a year. This will help production of crops or food supply and water supply available for living organism.
If the Earth's rotation is not tilted, then both the northern hemisphere and southern hemisphere will be covered with thick ice sheet. The equatorial region or near the equatorial region will experience tremendous warm temperature. Making our life on Earth not ideal for living.
Magnetic Field
Earth is protected by the magnetic from the dangerous radiation coming from the heat of the sun.
Water and oxygen
These two elements are essential for living organism in order to survive. The existence of waters proves that Earth temperature is conducive for living.
Answer: Precipitates form only in (b) (c) and (d) and these are 
, 
and NiS respectively.
Explanation: (a) The reaction will be:
The reaction will not take place as both the products are soluble and so no precipitate will form.
(b) The reaction will be:
This reaction will take place as aluminum hydroxide is insoluble. So, the precipitate formed in this reaction is .
(c) The reaction will be:
This reaction will take place as a precipitate of calcium sulfate(slightly soluble) will form.
(d) The reaction will be:
This reaction will take place as NiS is insoluble. So, the precipitate formed in this reaction is NiS.
