CBSE Class 12 Chemistry Question Paper 2018 with Solution PDF

By | March 7, 2019

CBSE Class 12 Chemistry Exam 2019 is scheduled to be carried out on 12 March, 2019 (Tuesday). While making ready for the board checks, each pupil is eager to understand the questions requested within the earlier years they usually additionally seek for the correct answers to all the ones questions.

In this newsletter, we’re offering the CBSE Class 12 Chemistry Solved Question Paper 2018. This paper won’t handiest lend a hand to understand the essential questions but in addition to put in writing correct rationalization to them. We have supplied an in depth technique to each and every query that comes to the correct key issues as discussed within the CBSE marking scheme.

All the answers had been collated within the type of PDF which scholars would possibly obtain to test the precise standards to put in writing very best examination and ranking prime marks.

Some of the questions and their answers from the CBSE Class 12 Chemistry Solved Question Paper 2018,are given under:

Q. Give causes for the next:

(a) Measurement of osmotic force way is most popular for the resolution of molar lots of macromolecules corresponding to proteins and polymers.

(b) Aquatic animals are extra at ease in chilly water than in heat water.

(c) Elevation of boiling level of 1M OkayCl resolution is just about double than that of one M sugar resolution.

Ans.

(a) Reasons to make use of osmotic force way are as follows:

  • As in comparison to different colligative homes, magnitude of osmotic force is huge even for extraordinarily dilute answers
  • Osmotic force may also be measured at room temperature while different colligative homes want both prime temp or low temp prerequisites. 
  • Macromolecules are most often now not solid at upper temperatures and polymers have deficient solubility.
  • Values of different colligative homes are very small {that a} small error can account to huge distinction.
  • In this technique, molarity of the answer is used as an alternative of molality.

(b) Because oxygen is extra soluble in chilly water or at low temperature.

(c) 1 mol of OkayCl ionises into 1 mol of Okay+ and 1 mol of Cl. So, the overall choice of ions get doubled. Since, elevation in boiling level is a colligative assets (relies on no. of molecules),so it will get doubled in case of OkayCl and stays similar in case of glucose which is a non-electrolyte.

Q. What occurs when

(a) a freshly ready precipitate of Fe(OH)3 is shaken with a small quantity of FeCl3 resolution?

(b) chronic dialysis of a colloidal resolution is performed?

(c) an emulsion is centrifuged?

Ans.

(a) Peptisation happens which results in the formation of a colloidal resolution of Fe(OH)3.

(b) Coagulation happens.

(c) Demulsification of immiscible combination happens which results in the separation of the constituent liquids.

CBSE Class 12 Mathematics Solved Question Paper 2018

Q. Give causes :

(a) Eo worth for Mn3+ /Mn2+ couple is a lot more certain than that for Fe3+/Fe2+.

(b) Iron has upper enthalpy of atomization than that of copper.

(c) Sc3+ is colourless in aqueous resolution while Ti3+ is colored.

Ans.

(a) Eo worth for Mn3+ /Mn2+ couple is a lot more certain because of the truth that Mn+2 has upper balance then Mn+3 because of part crammed d5 configuration.

(b) Iron has upper choice of unpaired electrons than that during copper because of which extent of covalent bonding is extra therefore enthalpy of atomization is extra.

(c) It is because of the absence of unpaired d-electron in Sc3+ while in Ti3+ there’s one unpaired electron which presentations d-d transition imparting color to its resolution.

Q. (a) Why is bithional added to cleaning soap?

(b) What is tincture of iodine? Write its one use.

(c) Among the next, which one acts as a meals preservative?

       Aspartame, Aspirin, Sodium Benzoate, Paracetamol

Ans.

(a) Bithional is added to cleaning soap to impart antiseptic homes.

(b) Tincture of iodine is 2-7 % elemental iodine alongside with potassium iodide or sodium iodide in mix of ethanol and water.

Use of tincture of iodine: It is used as an antiseptic and is carried out on minor cuts, scraps and burns to stop an infection.

(c) Sodium Benzoate paintings as meals preservative

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