The number of oxygen atoms bonded to one phosphorous atom in $P_4O_6$ is

The end correction for the vibrations of air column in a tube of circular cross-section will be more if the tube is

Box $A$ contains $2$ black and $3$ red balls, while Box $B$ contains $3$ black and $4$ red balls. Out of these two boxes, one is selected at random; and the probability of choosing Box $A$ is double that of Box $B$. If a red ball is drawn from the selected box, then the probability that it has come from Box $B$ is:

The practical purpose of classification of living organisms is to

The equation $x^2-5xy+py^2+3x-8y+2=0$ represents a pair of straight lines. If $\theta$ is the angle between them,then $\sin \theta$ is equal to

Which of the following groups of cells in the male gonad represents haploid cells?