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Which metal is purified by the liquation method?

The decomposition of azo methane, at a certain temperature according to the equation

$(C{H}_3{)}_2{N}_2\to C_2{H}_6+N_2$ is a first order reaction.

After $40$ minutes from the start, the total pressure developed is found to be $350$ mm Hg in place of initial pressure $200$ mm Hg of azo methane. the value of rate constant $k$ is:

(A) follows first order reaction, (A) $\to$ product.

The concentration of A changes from 0.1 to 0.025 M in 40 min.

Find the rate of reaction of A when the concentration of A is 0.01 M.

Which of the amino acids is not optically active?

Assertion: Phenolphthalein is an acid-base indicator.
Reason: In an acid-base titration, this indicator is used.

On what principle is chromatography based please explain me this very nicely because tomorrow is my exam

Question 1

Which of the following statements about the autotrophs is incorrect?



(a) They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll.

(b) They store carbohydrates in the form of starch.

(c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight.

(d) They constitute the first trophic level in food chains.

Ozone belongs to which group of the periodic table?

Question 3

List any three human activities which would lead to an increase in the carbon dioxide content of the air.

Match the following terms in Column - I with those in Column - II correctly. $\begin{array}{cccc}& \text{Column-I}& & \text{Column-II}\\ \text{a}.& \text{Aquatic animals}& 1.& \text{Sail boat}\\ \text{b}.& \text{Mountaineers}& 2.& \text{Soot and dust}\\ \text{c}.& \text{Factories}& 3.& \text{Oxygen cylinders}\\ \text{d}.& \text{Wind}& 4.& \text{Dissolved oxygen}\end{array}$

If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of

A certain sample of soil is used for testing the percolation rate. The amount of water taken is 400 ml and the percolation time measured is 10 mins. What is the percolation rate?

Question 4

Write the difference among solids, liquids and gases.

When baking soda and vinegar are mixed, the effervescence shows the evolution of ___.

What is the pH range at which our body works?

The given figure depicts the different regions of taste buds on our tongue. Match the different tastes- sweet, sour, salty and bitter with their respective regions.

If the rate constant for a first order reaction is k, the time (t) required for the completion of $99\%$ of the reaction is given by:

Water molecules form hydrogen bond among themselves due to___.

The amount of heat needed to melt $2kg$ of ice at its melting point, when latent heat of ice is $80cal/g$, is _____.

$(1cal=4.184J)$

How many moles of electron weigh 1 Kg?

Define the term fire triangle along with the components?

(a) Who gave the law of constant proportion?

(b) Write symbols of the following Ions :

(i) Ferric ion (ii) Calcium ion (iii) Peroxide ion (iv) Sulphate ion (v) Nitrate ion

When the surface of Earth is dug deeper and deeper, we reach a level where all the spaces between particles of soil and the gaps between rocks are filled with water. What is the upper limit of this layer called?

Which of the following condition is suitable for the formation of Nitric and Nitrogen Oxide?

Fill in
the blanks in the following statements:

(a) When carbon dioxide is passed through lime
water, it turns milky due to the formation of _________.

(b) The
chemical name of baking soda is _________.

(c) Two
methods by which rusting of iron can be prevented are _________
and

____
____.

(d) Changes in which only _____
__ properties of a substance change
are called physical changes.

(e) Changes
in which new substances are formed are called _________changes.