During the nuclear explosion, one of the products is ⁹⁰Sr with half life of 6.93 years. If 1 $$\mu $$ g of ⁹⁰Sr was absorbed in the bones of newly born baby in placed of Ca, how much time, in years, is required to reduce much time, in year, is required to reduce it by 90% if it not lost metabolically.

Two solutions, A and B, each of 100L was made by dissolving 4g of NaOH and 9.8 g of H₂SO₄ in water, respectively. The pH of the resultant solution obtained from mixing 40L of solution A and 10L of solution B is :

The number of orbitals associated with quantum number n = 5, m_s = +$${1 \over 2}$$ is :

What is the product of following reaction ?