Boron cannot form which one of the following anions?

(1) BO2-

(2) BF63-

(3) BH4-

(4) B(OH)4-

The electrochemical cell stops working after some time because ________

The hard Shell of an egg was dissolved in HCL. The egg was then placed in a concentration solution of NaCl. What will happens ______

Modern periodic table is based on atomic number of the elements. The significance of atomic number was proved by the experiment of ________

"If a system A is in thermal equilibrium with B and B is in thermal equilibrium with C, then A and C are in equilibrium with each other". This is a statement of 

TEL minimise the knocking effect when mixed with petrol, it acts as_______

Van der Waal's equation explains the behaviour of _____

Blue litmus paper is converted into red in solution of _______

Of the following elements, which one has the same oxidation  state in all of its compounds?