19,000+ solved questions for JEE Advanced, JEE Mains, NEET & IChO — with answers and expert explanations.
Correct pair of compounds, which gives blue colouration/ precipitate and white precipitate, respectively, when their Lassaigne’s test is separately done is (West Bengal JEE 2013)
The colour of the solution/precipitate obtained in the elemental analysis of an organic compound and the molecule/ion responsible for the colour are given below. Choose the incorrectly matched pair: (Kerala PET 2013 )
Kjeldahl's method cannot be used for the estimation of nitrogen in (AFMC 2013)
In the estimation of sulphur by Carius method 0.480 g of an organic compound given 0.699g of barium sulphide. The percentage of sulphur in this compound is (atomic masses : Ba = 137.5 = 32 and O = 16) (Kerala PET 2012)
A hydrocarbon contains 80% carbon. What is the empirical formula of the compound? (KCET 2009 )
1 percent composition of an organic compound A is carbon: 85.71% and hydrogen 14.20% . Its vapour density is 14. Consider the following reaction sequence Cl /H O (i) KCN/EtOH (ii) H O A B C -> -> Identify C (EAMCET 2…
The masses of carbon, hydrogen and oxygen in an organic compound are in the ratio 6: 1: 8 respectively. Which of the following pairs of formulae correspond to the above information? (Kerala CEE 2009) (a) CH O and CH …
In the Duma's method of estimation of nitrogen, the nitrogen in the organic compound is finally converted into (Kerala CEE 2009)
In an organic compound, C 68.5% and H 4.91% . Which empirical formula is correct for it? (CPMT 2009) (a) C H (b) C H O (c) C H O (d) C H O Ans. (b) Sol. Element At. Percent No. of Simple molar wt. composition moles …
A hydrocarbon has carbon and hydrogen. Its molecular weight is 28. Its possible formula would be (AFMC 2009) (a) C H (b) C H (c) CH (d) C H Ans. (b) Sol. Compound Molecular weight C H 12 3 x C H x CH C H x Henc…
Assertion (A): S || NH – C– NH gives red color in Lassaigne’s test Reason (R): Compounds having N along with C give red colour in Lassaigne’s test. (AIIMS2009)
Assertion (A): Oils are purified by steam distillation. Reason (R): The compounds which decompose at their boiling points can be purified by steam distillation. (AIIMS2008)
Assertion (A): During test for nitrogen with Lassaigne’s extract on adding FeCl3 solution sometimes a red precipitate is obtained. Reason (R): Sulphur is also present (AIIMS2007)
Anthracene can be purified by
Steam distillation is used only in case of steam volatile substance. Hence (c) is not correct. 4. Vaccum distillation is used in liquids which decompose at their boiling Point. Hence (d) is incorrect.
CCl4 & acetone differ in their boiling Point. So it can be seperated through fractional distillation. Hence (b) is correct.
Azeotropic distillation is used only to seperate azeotropes ie. constant boiling mixture. Here acetone & CCl4 are not azeotropic mixture. Hence (a) is not correct.
A mixture of acetone and CCl4 can be separated by
If N and S both are present in an organic compound during Lassaigne’s test, both will change into
The prussian blue colouration obtained in the test for nitrogen in the organic compound is
Sodium nitrorusside Na2[Fe(CN)5NO] is used as reagent for detection of ______ and the compound formed is ____.
Will you get any precipitate if you add silver nitrate solution to chloromethane? If not, why?
How is phosphorus estimated in an organic compound?
What type of organic compounds cannot be Kjeldahlised?
What conclusion would you draw if during Lassaigne‘s test, a blood red colouration is obtained?