Home
Class 7
CHEMISTRY
A metal tray was used to cover a beaker ...

A metal tray was used to cover a beaker of boiled water as shown in the diagram. The beaker and metal tray were then removed from the tripod stand and left on the table. After two minutes, which of the following can be observed?

A

B

C

D

Text Solution

Verified by Experts

The correct Answer is:
B
Promotional Banner

Similar Questions

Explore conceptually related problems

In an experiment, a heated cup of coffee is removed from a heat source, and the cup of coffee is then left in a room that is kept at a constant temperature. The graph above shows the temperature, in degrees Fahrenheit (.^@F) , of the coffee immediately after being removed from the heat source and at 10-minute intervals thereafter. During which of the following 10-minute intervals does the temperature of the coffee decrease at the greatest average rate?

Three metallic plates out of which the middle is given charge Q as shown in the figure. The outer plates can be earthed with the help of switches S_1 and S_2 . The area of each plates is the same. Answer the following question based on the given passage. ,brgt The charge appearing on the outer surface of extreme left plate is

Metals are extracted from their ores by a wide variety of techniques. The most common ores are oxides. Most metals are obtained by direct treatment of theirs ores with chemical agents, but the extraction of certain others require electrolysis. An example of the former type of process is the extraction of iron from its oxide, described by the following equation : Fe_(2) O_(3) + 3C rarr 2Fe + 3CO The relative ease of extraction of a metal from its oxide can be estimated using the Ellingham diagram, as shown in the figure. The diagram plots the free energies of formation of various oxides per mole of consumed oxygen as a function of absolute temperature. Which of the following best explains why the free energy of formation of Fe_(2)O_(3) becomes less negative as the temperature is increased.

Two metal rods X and Y having equal cross-sectional areas are joined in series. One end of which is heated. After some time, the temperature gradient along each rod is foound to be uniform, but greater in X than that in Y. Which of the following can be inferred

A positive point charge is placed at P in front of an earthed metal sheet S.Q and R are two points between P and S as shown in the diagram. If the electric field strength at Q and r are respectively E_(Q) and E_(R) , which one of the following statement is // are false?

A well-watered healthy potted plant with variegated leaves was kept in darkness for about 24 hours. It was then set-up as shown in the diagram below and exposed to light for about 12 hours. At the end of this time, leaf X and leal y were tested for starch. Study the diagram and answer the questions that follow Select the correct leaf from the five available choices shown in the diagram as A, B, C, D and E Rewrite the correct answer by filling in the appropriate letter for the questions that follow : After the starch test, leaf X would look like ........

A well-watered healthy potted plant with variegated leaves was kept in darkness for about 24 hours. It was then set-up as shown in the diagram below and exposed to light for about 12 hours. At the end of this time, leaf X and leal y were tested for starch. Study the diagram and answer the questions that follow Select the correct leaf from the five available choices shown in the diagram as A, B, C, D and E Rewrite the correct answer by filling in the appropriate letter for the questions that follow : After the starch test, leat Y would look like ................

Despite the fact that aluminium is a reactive metal, it is a stable in air as well as in water. This is due to the formation of thin layer of oxide on the surface of aluminium metal which makes it passive for further attack. The layer is so useful, that in industry, it is purposely deposited by an electrolytic process called anodising. Reaction of aluminium with oxygen is highly exothermic and is called thermite reaction. 2Al_((s)) +(3)/(2) O_(2(g)) rarr Al_(2)O_(3(s)) Delta_(f) H^(Ө) = -1670 kJmol^-1 This reaction finds application for welding of metal and in the metallurgical extraction of many metals from their oxides. The limitation is that to start the reaction, high temperature is required for which an ignition mixture is required. Which of the following metals cannot be extracted by using Al as a reducing agent ?

Choose the correct option: Three blocks of identical masses are placed on a frictionless table as shown . The centre block is at rest , whereas the other two blocks are moving directly towards the stationary block with identical speed v . The centre block is initially closer to the left block than the right one . All collisions are elastic . After long time , which of the following is true .