$A$ patient brought to a hospital with myocardial infarction is normally immediately given

In the Davisson-Germer experiment, an electron beam of energy $75 \ eV$ falls normally on the surface of a crystal. If the maximum intensity is obtained at an angle of $45^{\circ}$ to the direction of the incident beam, then the inter-atomic distance in the lattice plane of the crystal will be :-............... $\mathring{A}$

Which of the following sulfate salts has the highest solubility in water?

The incorrect statement regarding the following reactions is:
$XeF_6 + \text{Excess } H_2O \rightarrow 'X' + HF$
$XeF_6 + 2 H_2O \rightarrow 'Y' + HF$

$\sum_{k=1}^{\infty} \frac{1}{k!}\left(\sum_{n=1}^k 2^{n-1}\right)$ is equal to

In which of the following pairs do both species have $sp^3$ hybridization?