The species having tetrahedral shape is

$A$ vertical $U-$tube of uniform inner cross-section contains mercury in both sides of its arms. $A$ glycerin (density $= 1.3 \ g/cm^3$) column of length $10 \ cm$ is introduced into one of its arms. Oil of density $0.8 \ g/cm^3$ is poured into the other arm until the upper surfaces of the oil and glycerin are in the same horizontal level. Find the length of the oil column. (Density of mercury $= 13.6 \ g/cm^3$) (in $cm$)

Glucose and mannose are

Which of the following statements is consistent with the Kingdom Fungi?

Keystone species deserve protection because these

If $3x^2-11xy+10y^2-7x+13y+k=0$ denotes a pair of straight lines,then the point of intersection of the lines is