Which of the following has the lowest melting point?

$A$ parallel beam of fast-moving electrons is incident normally on a narrow slit. $A$ screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is $\text{CORRECT}$?

Which of the following is not correct regarding the properties of ionic compounds?

Read the following five statements and answer the question.
$(a)$ In $Equisetum$ the female gametophyte is retained on the parent sporophyte.
$(b)$ In $Ginkgo$ male gametophyte is not independent.
$(c)$ The sporophyte in $Riccia$ is more developed than that in $Polytrichum$.
$(d)$ Sexual reproduction in $Volvox$ is isogamous.
$(e)$ The spores of slime molds lack cell walls.
How many of the above statements are correct?

The decomposition of $N_2O_5$ is a first order reaction represented by $N_2O_5 \to N_2O_4 + \frac{1}{2}O_2$. After $15 \ min$,the volume of $O_2$ produced is $9 \ mL$ and at the end of the reaction,it is $35 \ mL$. The rate constant is equal to:

What is the primary cause of coronary artery disease $(CAD)$?