The answer I believe would be D) All of these
Answer:

Explanation:
Helo,
In this case, the pressure must be computed as follows:

Which is using the density of mercury (13.6 g/mL) and its height, thus, we obtain (using the proper units):

Best regards.
20 g O2 x 1 mol O2/32 g O = 0.625 mol O2
Answer:-
Water is highly ordered. In water each oxygen atom is connected to others around it through hydrogen bonding via bridging hydrogen atoms. When a salt like NaCl is dissolved, some of these Hydrogen bonds break.
When a salt like NaCl dissolves in water, the NaCl breaks in to ions Na+ and Cl-.
The water molecules now surround these ions.
The slightly negative oxygen end of water molecule gets near the Na+, while the slightly positive Hydrogen of water molecule gets near the Cl-.
So before salt sample dissolve, the water molecules were highly ordered due to hydrogen bonding. Now after salt dissolve there is a decrease in order and thus an increase in disorder of the water molecules.
Due to increase in disorder, entropy which is a measure of disorder increases. Since entropy increases, delta S for the process is positive.
Answer:
1
only 4 is the significant figure
we take tailing zeroes as significant figures only in case of decimals