Answer:
We only know it's there because we can see the effect of its gravity. Scientists study dark matter by looking at the effects it has on visible objects. Scientists believe that dark matter may account for the unexplained motions of stars within galaxies. Computers play an important role in the search for dark matter information.
Explanation:
Hope That helps!
Answer:
molding sand, washed sand, beach sand, mason sand, and silica sand
Explanation:
they all have different features and are better for certain things, for example some of silica sands features are
Molecular Weight: 60.084 g/mol
Exact Mass: 59.966756 g/mol
Boiling Point: 4046°F at 760 mm Hg
Melting Point: 3110°F
The given is incomplete as the options are missing. The correct options for the given question are as follows-
(A) cultivation of agricultural land inhibits the decomposition of organic matter
(B) nitrogen-fixing bacteria are not as plentiful in agricultural soils because of the use of pesticides
(C) land that is available for agriculture tends to be nutrient-poor
(D) the nutrients that become the biomass of plants are not cycled back to the soil on lands where they are harvested
Answer:
Option (D)
Explanation:
In order to carry out agricultural practices, the soil must be rich in essential nutrients for the growth of crops. The soil fertility is a key role in the production of crops.
This agricultural land often requires a large amount of these nutrients and minerals because some of the nutrient minerals are converted into plant biomass which is then used up to produce energy in other sectors. So, the nutrients that were present in the soil are taken away and not transferred back into the soil. This means that the nutrient cycle gets affected. Due to this reason, there requires a constant supply of nutrients into the agricultural fields.
Thus, the correct answer is option (D).
