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
A COMPLETE FERTILISER BECAUSE OF THE PHOSPHORUS IN THE FIELD IS LIMITED. BUT DEPENDING ON THE OTHER NUTRITION IN THE SOIL. PLEASE MARK ME BRAINLIST
Answer : The concentration of NaOH is, 0.336 M
Explanation:
To calculate the concentration of base, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is NaOH.
We are given:

Putting values in above equation, we get:


Thus, the concentration of NaOH is, 0.336 M
<u><em>Your Essay Must include:</em></u>
<u><em>Introduction:Brings the main idea,Must be atleast 3 sentences.</em></u>
<u><em>Body/Details:Supports the main Idea,Must be atleast 8 sentences.</em></u>
<u><em>Body/Details(Optional):Supports the main Idea,Must be atleast 8 sentences.</em></u>
<u><em>Conclusion:Tells a little more information.</em></u>