The structure of $Na_2[B_4O_5(OH)_4] \cdot 8H_2O$ contains:

Which of the following is the correct decreasing order of Lewis acid strength of boron halides?

Which of the following statements is incorrect for $B_2H_6$?

What does orthoboric acid contain?

Aluminum dissolves in mineral acids and aqueous alkalis and thus shows amphoteric character. $A$ piece of aluminum foil is treated with dilute hydrochloric acid or dilute sodium hydroxide solution in a test tube and on bringing a burning match stick near the mouth of the test tube,a pop sound indicates the evolution of hydrogen gas. The same activity when performed with concentrated nitric acid,the reaction does not proceed. Explain the reason.

Which of the following statements about boron carbide is wrong?