Most abundant gas in the atmosphere ; plants absorb it from bacteria in the soil

The most abundant has in the atmosphere is NItrogen.

Explanation:

Nitrogen is the most important gas in the atmosphere, it's account for about 78% of total gas in the atmosphere.

Plants cannot absorb nitrogen directly from the atmosphere it most first be converted to soluble ions because nitrogen gas is unreactive. Nitrogen is converted to nitrate by nitrogen fixing bacteria in the soil, through root nodules of leguminous plants and lightening. In this form, plants absorb nitrogen and use it to make chlorophyii. Chlorophyii is an essential pigment in green plants needed for photosynthesis.

Answer;

Basaltic igneous rock

Explanation;

-Basaltic igneous rock is dense and has a dark color.

Igneous is among the three types of rocks, others being sedimentary and metarmophic rocks. It is formed as a result of cooling and solidification of magma or lava.

-Basalt is an extrusive igneous rock that is dark in color, and occurs in the ocean bedrock and may also occur on land in extensive flows of lava. Additionally, basalt contains fine grains and is composed of mainly pyroxene and plagioclase minerals.