What is the arrow pointing to?
the figure shows a solution of different molecules. some of them consist of two small atoms attached to a bigger one. some are negatively charged, and consist of one big atom attached to the small one. there are also small positively charged atoms, which are pointed by an arrow.
a. hydrogen ion
b. hydronium ion
c. electron
d. hydroxide ion
e. water molecule

Option A

Explanation:

Hi, this is why A is the correct option:

Hydronium ion ( ), water ( ) and hydroxide ion () are all molecules formed by two or more atoms.

So the correct answer is between hydrogen ion and electron. Well the diference is that the first one is positively charged (as the atom pointed) and the second one is negatively charged.

By elimination of the other options, the right one is option A

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.