Which of the following are not electromagnetic waves?

The number of non-trivial solutions of the system $x-y+z=0, x+2y-z=0, 2x+y+3z=0$ is

Which of the following pairs of transition metal ions have the same calculated values of magnetic moment?

Assertion : Both $Be$ and $Al$ can form complexes such as $BeF_4^{2-}$ and $AlF_6^{3-}$ respectively,$BeF_6^{3-}$ is not formed.
Reason : In case of $Be$,no vacant $d-$orbitals are present in its outermost shell.

$A$ parallel plate capacitor with air between the plates has a capacitance of $9 \, pF$. The separation between its plates is $d$. The space between the plates is now filled with two dielectrics. One of the dielectrics has dielectric constant $K_1 = 3$ and thickness $d/3$,while the other one has dielectric constant $K_2 = 6$ and thickness $2d/3$. The new capacitance of the capacitor is ........ $pF$.

'Himgiri' developed by hybridization and selection for disease resistance against rust pathogens is a variety of