Which of the following are correct?
i. Basic structural unit of silicates is –\( \text{-RSiO-} \)
ii. Silicones are biocompatible
iii. Producer gas contains CO and \( \text{N}_2 \)

1 gram of sodium hydroxide was treated with 25 ml. of 0.75 M HCI solution, the mass of sodium hydroxide left unreacted is equal to :
Identify Z in the following reaction sequence.

 
If the roots of $\sqrt{\frac{1 - y}{y}} + \sqrt{\frac{y}{1 - y}} = \frac{5}{2}$ are $\alpha$ and $\beta$ ($\beta > \alpha$) and the equation $(\alpha + \beta)x^4 - 25\alpha \beta x^2 + (\gamma + \beta - \alpha) = 0$ has real roots, then a possible value of $y$ is: