Which of the following oxides will produce hydrogen peroxide upon reaction with dilute acid?

Observe the following lists. Then the correct match for List-$I$ from List-$II$ is:

List-$I$	List-$II$
$(A)$ $[\mathbf{a} \mathbf{b} \mathbf{c}]$	$1. |\mathbf{a}||\mathbf{b}|\cos(\mathbf{a}, \mathbf{b})$
$(B)$ $(\mathbf{c} \times \mathbf{a}) \times \mathbf{b}$	$2. (\mathbf{a} \cdot \mathbf{c})\mathbf{b} - (\mathbf{a} \cdot \mathbf{b})\mathbf{c}$
$(C)$ $\mathbf{a} \times (\mathbf{b} \times \mathbf{c})$	$3. \mathbf{a} \cdot \mathbf{b} \times \mathbf{c}$
$(D)$ $\mathbf{a} \cdot \mathbf{b}$	$4. |\mathbf{a}||\mathbf{b}|$
	$5. (\mathbf{b} \cdot \mathbf{c})\mathbf{a} - (\mathbf{a} \cdot \mathbf{b})\mathbf{c}$

$A$ piece of copper and another of germanium are cooled from room temperature to $80\,K$. Which of the following is a correct statement?

What is a portal system?

The distribution of relative intensity $I(\lambda )$ of blackbody radiation from a solid object versus the wavelength $\lambda $ is shown in the figure. If the Wien displacement law constant is $2.9 \times 10^{-3}\ mK$,what is the approximate temperature of the object in $K$?

Which one of the following orders presents the correct sequence of the increasing basic nature of the given oxides?