NEET Chemistry Questions: Some Basic Concepts in Chemistry

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In an experiment, 4 gm of $ M_2O_x $ oxide was reduced to 2.8 gm of the metal. If the atomic mass of the metal is 56 gm/mol, the number of oxygen atoms in the oxide is (AFMC 2010)





$ 1 Mol M_2O_x = (2 \times 56 + 16x) gm$ $ Now, (2 \times 56 + 16x) gm of oxide = 112 gm metal $ $ \therefore 4 gm of oxide = { 112 \times 4 \over 112 + 16x } gm metal $ $ But { 112 \times 4 \over 112 + 16 x } = 2.8 (given ) \therefore x = 3 $

Match the following Column - I (i) femto (ii) yotta (iii) giga (iv) atto Column - II (P) $ 10^9 $ (q) $ 10 ^{-15} $ (r) $ 10 ^ {-18} $ (s) $ 10 ^ {24} $




No explanation available.
The total number of atoms of all elements present in mole of ammonium dichromate is




Molecular formula of ammonium dichromate is $ (NH_4 )_2 Cr_2O_7 $
0.32 gm of a metal on treatment with an acid gave 112 mL of hydrogen at STP. Calculate the equivalent weight of the metal




$$ Eq. wt of metal = { wt of metal \times 11200 \over vol.of H_2 in ml displaced at STP } $$
For a reaction A + 2B  C, the amount of C formed by starting the reaction with 5 moles of A and 8 moles of B is




In the balanced chemical equation A + 2B → C, the stoichiometric coefficients indicate that 1 mole of A reacts with 2 moles of B to produce 1 mole of C. Given that the reaction starts with 5 moles of A and 8 moles of B, the limiting reactant is A (5 moles). Therefore, the maximum amount of C that can be formed is 4 moles.

100 mL of $PH_3$ on heating forms P and $H_2$ . The volume change in the reaction is





$ 2PH_{3_{(g)}} \rightarrow 2P_{(s)} + 3H_{2_{(g)}} $ 2mL 3mL $ \therefore 100ml (?) $ = { 100 \times 3 \over 2 } = 150ml $ $ \therefore Increase = 50mL $

An organic compound made of C, H, and N contains 20% nitrogen. Its molecular weight is (WBJEE 2009)




No explanation available.

An ore contains 1.24% of the mineral argentite $ Ag_2S$ by mass. How many grams of this ore would have to be processed in order to obtain 1.0 g of pure solid silver ?





$ Ag_2S $ Ag ore $ Ag_2 S $ 248g 216g 100g 1.24g (?) $ \therefore1.0g (?) 1.148g = 1.148g $ = 92.58 \approx 92.6 g $

Find the electric charge in coulumb of 9.0 gm of $ Al ^ {3+} $ ions.




$ No. of moles of Al ^ {3+} = { 9 \over 27 } = 0.33 $ $ \therefore No. of Al ^ {3+} ions = 0.33 \times 6.022 \times 10 ^ {23} = 2 \times 10 ^ {23} $ $ \therefore Electric charge = 3 \times 1.602 \times 10 ^ {-19} \times 2 \times 10^ {23} = 9.6 \times 10 ^ {+4} $ Coulomb
Which of the following is not a homogeneous mixture ?




No explanation available.

27 g of Al (at mass = 27) will react with oxygen equal to (IIT 1978)





No explanation available.
Which of the following pairs of substances illustrates the law of multiple proportions ?




The law of multiple proportions states that when two elements form more than one compound, the masses of one element that combine with a fixed mass of the other element are in a ratio of small whole numbers. This law is illustrated by the compounds CO and CO₂.
In each of the follwoing questions, two statements are given, one is Assertion (A) and the other is Reason (R). Examine the statements carefully and mark the correct answer according to the instructions given below : A : Normality of 0.1M $ H_2SO_4$ is 0.2N. R : $ H_2SO_4 $ is a dibasic acid.




No explanation available.
In each of the follwoing questions, two statements are given, one is Assertion (A) and the other is Reason (R). Examine the statements carefully and mark the correct answer according to the instructions given below : A : 1 Gram molecule of sulphar also represents 1 gram atom of sulphur. R : Atomicity of sulphur is one.




No explanation available.
In each of the follwoing questions, two statements are given, one is Assertion (A) and the other is Reason (R). Examine the statements carefully and mark the correct answer according to the instructions given below : A : In the equation $ NH_ 3 + HCl \rightarrow NH_4 Cl, , Gay-Lussac’s law is not applicable to NH_4Cl $ . R : $ NH_4Cl$ is not a gas,.




Gay-Lussac's law states that gases combine or are produced in volumes that bear a simple ratio to one another. Since NH4Cl is a solid, not a gas, Gay-Lussac's law is not applicable to it. Both the assertion and reason are correct, and the reason correctly explains the assertion.