There are O-H bonds in H2O. They have the intramolecular force of polar covalent bond.
Reaction of option c produces precipitate.
Rhodium on reacting with potassium phosphate produces rhodium phosphate which remain in solution due to low lattice energy for rhodium phosphate.
Niobium on reacting with lithium carbonate produces niobium carbonate and it will remain in aqueous form.
Cobalt on reacting with zinc nitrate produces cobalt nitrate. This, Co(NO3 )2 is insoluble precipitate and settles at bottom whereas zinc ion will remain in solution as follows:

Potassium ion on reacting with sodium sulfide produces potassium sulfide which remain in solution
Answer:
1. See explanation below
2. Density
3. Masses
Explanation:
1. Your picture is a bit too small to see the values but maybe this will help you.
To determine the maximum maximum mass in grams that triple beam balance can measure all you have to do is add up the maximum of each beam. So all you need to do is see the value at the last notch of each beam.
However, if you are referring to the picture that is attached in the bottom: The answer would be 610g. Because the last notches of each beam are as follows:
100 g
500 g
10 g
So we add that we get 610g.
2. density can be computed using the formula:
D = M/V
where:
D = density
M = mass
V = volume
As you can see in the both figures A and B measure 20 g, this means that their masses are the same. The density of objects can be different when either their masses, or their volumes are different. So even if they have the same mass, they can have different densities because they have different volumes.
3. Force of gravitational attraction between two objects is dependent on the masses of the two objects and the distance. The larger the mass, the stronger the gravitational force of attraction. This means that they have a direct relationship. Now when it comes to distance, the further apart they are the weaker the gravitational force of attraction, or in other words, they are indirectly related.
Not strong base and acid, not dissolved or not aqueous.