Which from following reagents is used to identify straight chain of glucose?

Which of the following aldehyde has buttery odour?

At $$300 \mathrm{~K}, 22 \mathrm{~g}$$ of $$\mathrm{CO}_2$$ gas exerts a pressure of 5 atmosphere. What is the volume of the gas at the same temperature? $$(\mathrm{R}=0.0821 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1})$$

Which among the following is NOT benzylic halide?