Questions

The size of the pupil of the automatically adjusts itself according to the intensity of light passing through it; if the intensity is more, the size is less, if less, it is more. So in our case the pupil should dilate i.e , increase in size to be able to see in the dark. This switchover takes some time. But here the entry into the dark room is immediate. So the eye has no time to adjust itself and hence is not able to see at all for a while. 

In chemistry, the term transition metal has three possible meanings: The IUPAC definition defines a transition metal as "an element whose atom has a partially filled d sub-shell, or which can give rise to cations with an incomplete d sub-shell".

Any of the set of metallic elements occupying a central block (Groups IVB–VIII, IB, and IIB, or 4–12) in the periodic table, e.g. iron, manganese, chromium, and copper. Chemically they show variable valency and a strong tendency to form coordination compounds, and many of their compounds are coloured.

Here in the given options, only iron (Fe) is a transition metal since Strontium is an alkaline earth, arsenic is a metalloid, hydrogen is (normally) a diatomic gas.

Paper production is basically a two-step process in which a fibrous raw material is first converted into pulp, and then the pulp is converted into paper. The harvestedwood is first processed so that the fibres are separated from the unusable fraction of the wood, the lignin. Pulp making can be done mechanically or chemically. In the chemical pulping process, alkali (e.g., sodium hydroxide in the form of a lye or caustic soda) is usually used to remove the lignin that binds the fibres. So, for degumming of raw material, caustic soda is used.

High frequency sound attacks the tympanic memberane and makes it defective. 120 decibles is too high a pitch to be heard and therefore it impairs the hearing ability.

Hooke's law states that within the elastic limit, stress developed is directly proportional to the strain produced in a body.Hooke’s law is valid only in the linear part of stress-strain curve. Hence, statement 1 is correct.