The strength of 11.2 volume solution of H₂O₂ is : [Given that molar mass of H = 1 g mol–1 and O = 16 g mol^–1]

For the solution of the gases w, x, y and z in water at 298K, the Henrys law constants (K_H) are 0.5, 2, 35 and 40 kbar, respectively. The correct plot for the given data is :-

The minimum number of times one has to toss a fair coin so that the probability of observing at least one head is at least 90% is :

A student scores the following marks in five tests :

45, 54, 41, 57, 43.

His score is not known for the sixth test. If the mean score is 48 in the six tests, then the standard deviation of the marks in six tests is