What is the use of potassium dichromate $(K_2Cr_2O_7)$?

$I$. Two non-zero,non-collinear vectors are linearly independent.
$II$. Any three coplanar vectors are linearly dependent.
Which of the above statements is/are true?

The binding energy per nucleon versus mass number curve for nuclei is shown in the figure. $W, X, Y$ and $Z$ are four nuclei indicated on the curve. The process that would release energy is:

$A$ telescope has an objective lens of focal length $200 \ cm$ and an eyepiece with focal length $2 \ cm$. If this telescope is used to see a $50 \ m$ tall building at a distance of $2 \ km$,what is the height of the image of the building formed by the objective lens in $cm$?

Which one of the following equations represents the variation of viscosity coefficient $(\eta)$ with temperature $(T)$?

Five elements $A, B, C, D$ and $E$ have work functions $1.2 \ eV, 2.4 \ eV, 3.6 \ eV, 4.8 \ eV$ and $6 \ eV$ respectively. If light of wavelength $4000 \ \mathring{A}$ is allowed to fall on these elements,then photoelectrons are emitted by: