What will be the ratio of de-Broglie wavelengths of a proton and an $\alpha$-particle of the same energy?

Which of the following oxides cannot act as a reducing agent?

$Fe_2Cr_2O_4 + Na_2CO_3 + O_2$ $\xrightarrow{\text{Fusion}} [X]$ $\xrightarrow[H_2O]{H^+} [Y]$ $\xrightarrow{H_2O_2/H^+} [Z]$
Which of the following statements is true for the compounds $[X], [Y]$ and $[Z]$?

In a meter bridge experiment,a resistance of $9 \Omega$ is connected in the left gap and an unknown resistance $x$ (where $x > 9 \Omega$) is connected in the right gap. If the resistances in the gaps are interchanged,the balancing point shifts by $10 \text{ cm}$. The value of the unknown resistance is: (in $Omega$)

The technique used to make numerous copies of a specific segment of $DNA$ quickly and accurately is

The Poisson's ratio of a material is $0.5$. If a force is applied to a wire of this material,there is a decrease in the cross-sectional area by $4 \%$. The percentage increase in the length is ........ $\%$