<span> the atmosphere holds about 21 per cent oxygen. Over the Earth’s 4.6 billion year history, oxygen did not appear in the atmosphere until perhaps about 2.5 billion years ago. Since then, oxygen levels have fluctuated in tandem with global geological and biological events, such as mass extinctions.</span>
Answer:
Trade winds
Explanation:
I am not sure
The correct answer is C. Compounds have different properties than their component elements. When compounds are formed, they undergo change resulting to changes in the properties they exhibit. It will have its new set of properties different from the elements.
Answer:
B
Explanation:
Assuming the units are all supposed to be the same
A cube shaped cell with a 1 um³ volume would have a dimensions of 1 x 1 x 1 (because volume = length x width x height and 1 x 1 x 1 =1)
If we double the dimensions, we have a cube with the dimensions 2 x 2 x 2.
The surface area of each face of the cube is the length x width, so 2 x 2. This means the surface area of each face of the cube is 4 um².
There are 6 faces of a cube, so the total surface area is 6 x 4 um² = 24 um².
<span>PV=nRT= a universal constant
For any condition
P1V1/n1T1=R
and
P2V2/n2T2=R
i.e
P1V1/n1T1=P2V2/n2T2
Becomes
V1/n1=V2/n2
rearranging and solving
V2=V1X(n2/n1)= 750 mLx((0.65+0.35)/(0.65))=1200ml=1.2L...2 sig figs</span>
