Exercise

The picture shows the arrangement of particles in three different substances.

Which of the following is true about the state of the three substances?

The picture shows the arrangement of particles in three different substances.

What can be done to make the particles of Substance $1$ move slower?

Two students X and Y have to do their experiment on plotting the temperature-time graph for a hot body as it cools to room temperature. They do their experiments in the same lab, using completely identical apparatus, take equal amounts of tap water heated up to the same temperature, start their observations simultaneously and note the temperature values at identically spaced intervals of time. Their temperature-time graphs, plotted on a given graph paper, with the same given choices of scales along the axis, are however, as shown: The following could be the reason for this difference:

(A) Use of an overhead fan by student X.
(B) Use of an overhead fan by student Y.
(C) Less frequent stirring of water by student X.
(D) Less frequent stirring of water by student Y.
The most likely reason is:

The graph given below represents the interconversion of ice to water vapour. Identify the point in the curve which indicates the boiling point of water.

Aqueous lead (II) nitrate and aqueous potassium iodide are added to a dish containing water as shown.

A yellow precipitate forms after a few minutes.

Which process occurs before the precipitate forms?

A student sets up an apparatus to determine the melting point of ice. He takes a beaker half filled with crushed ice and dips a mercury thermometer with an initial reading of room temperature $25°\mathrm{C}$ in such a way that the bulb of the thermometer is surrounded by ice. The correct observation obtained by the student is that:

When two substances A and B of same mass are heated under similar conditions, number of free surfaces has been found to reduce to zero from one. If A maintains constancy in the temperature for a longer time than B during heating, then

Dimethyl ether decomposes as:

${\mathrm{CH}}_3{\mathrm{OCH}}_3\left(\mathrm{g}\right)\to {\mathrm{CH}}_4\left(\mathrm{g}\right)+\mathrm{CO}\left(\mathrm{g}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

When ${\mathrm{CH}}_3{\mathrm{OCH}}_3$ decomposes to $20\%$ extent to a certain fixed conditions, what is the ratio of rate of diffusion of pure ${\mathrm{CH}}_3{\mathrm{OCH}}_3$ with methane.