B.)<span>A doctor would use technetium-99m because a short half-life indicates a quick measurement, and a geologist would use rubidium-87 because a longer half-life means that there is a longer time to measure old rock. </span>
Answer:
C. 0.4.
Explanation:
<em>∵ mole fraction of acetic acid (X acetic acid) = (no. of moles acetic acid)/(total no. of moles) = (no. of moles acetic acid)/(no. of moles of acetic acid + no. of moles of water).</em>
<em></em>
- no. of moles of acetic acid = 2, no. of moles of water = 3.
- Total no. of moles = no. of moles of acetic acid + no. of moles of water = 2 + 3 = 5.
<em>∴ mole fraction of acetic acid (X acetic acid) = (no. of moles acetic acid)/(total no. of moles) =</em> (2)/(5)<em> = 0.4.</em>
Answer:
C. Moon, Earth, Jupiter, Sun
Explanation:
Well, the moon is smaller than the Earth so, C is the only logical explanation
The way most metamorphic rock<span> is formed. Change in </span>rock is the result<span> of metamorphism over a large area. </span>Type of rock<span> texture that </span>results<span> when </span>extreme pressure<span> causes minerals in metamorphic </span>rock<span> to realign, or when minerals separate out into dark and light bands.</span>
Answer:
A soap or alcohol will interfere with the hydrogen bonding between water molecules making it weaker
Explanation:
A water molecule is polar as the oxygen atom is strongly electronegative and draws the electrons it shares with the hydrogen atoms in the water molecule to itself. This creates a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms. The attraction of neighboring oxygen to hydrogen atoms in a water molecule results in hydrogen bonding.
However, a detergent molecule which has a polar head and a hydrophobic tail, when added to water significantly interferes with the hydrogen bonding between water molecules. The polar head is attracted to water molecules whereas the hydrophobic tail of each molecule are not. The detergent molecules form clusters known as micelles with the polar heads attracted to water and the hydrophobic tails directed towards the center of the micelle, away from water molecules. This weakens the hydrogen bonding between water molecules
An alcohol contains a polar -OH group in its molecules. However, the hydrogen bonding between alcohol molecules are weaker than that in water because the other end of the alcohol molecule has a C-O bond which is less polar than the O-H bond. Therefore, when an alcohol is added to water, it weakens the hydrogen bonding in water.
This weakening of the hydrogen bonding in water also has the effect of lowering the surface tension of water.
