Which of the following is considered an acellular organism?

When did $R.H. Whittaker$ propose the five-kingdom classification system?

Zero growth means:

In order to double the frequency of the fundamental note emitted by a stretched string,the length is reduced to $\frac{3}{4}$ of the original length and the tension is changed. The factor by which the tension is to be changed is

The given graphs $I$,$II$,and $III$ represent general trends observed for different physisorption and chemisorption processes under mild conditions of temperature and pressure. Which of the following statements are correct?

If the harmonic mean of the roots of the equation $\sqrt{2}x^2 - bx + (8 - 2\sqrt{5}) = 0$ is $4$,then the value of $b$ is: