Chemastro

CHEMISTRY OF HENNA The chemistry of henna (Lawsonia inermis) is very interesting - it is an amalgamation of organic chemistry, natural dyes, and skin chemistry. Let’s break it down simply 1. Source The henna is derived out of the leaves of the plant Lawsonia inermis. Lawsone is the active dye molecule of henna. Chemical name: 2-hydroxy-1,4-naphthoquinone Molecular formula: C₁₀H₆O₃ Form: It is a naphthoquinone analog of anthraquinone-type dyes. 2. Chemistry of Lawsone Functional groups: Hydroxyl group (-OH) Two (carbonyl) C=O groups in quinone ring. This renders lawsone a weak acid and provides the latter with the capacity to develop hydrogen bonds and react with proteins. 3. Mechanism /How Henna stains Skin/Hair When henna paste is applied: The molecules of lawsone permeate the epidermis or hair. They attach themselves to keratin which is the major protein on the hair and skin. It reacts by Michael addition - the quinone group in lawsone reacts with the amino groups...

 10 basic questions in Organic Chemistry for Scientific assistant (PYQS) 1. How many electrons occupy bonding molecular orbitals of CN triple bond? 2 4 6 8 Answer: 6 electrons Explanation: CN has a triple bond which means it has one sigma bond and one pi bond. One sigma bond contains two electrons and one pi bond contains 4 electrons which means CN triple bond contains a total of 6 bonding electrons 2. Which of the following compounds is most acidic? CH3CH2OH CH3COOH CH3NH2 CH3Cl Answer: CH3COOH Explanation: CH3CH2OH is very weak acid its conjugate base is not resonance stabilized                       CH3COOH is acidic and its conjugate base is resonance stabilized                       CH3NH2 is a base                       CH3Cl is neutral not acidic 3. Which of the following is an example of ...

10 EASY QUESTIONS IN INORGANIC CHEMISTRY 1. What is the oxidation state of Sulphur in H2SO4? +2 +3 +6 +4        Answer: +6  Explanation: Oxidation states of  Hydrogen, Oxygen are +1, -2, Substitute in formula,                      2(1)+x+4(-2) = 0                                        x = +6 2. What is the gas evolved when Zinc reacts with HCl? Cl2 H2 O2 HCl Answer: H2 Explanation: Zn + dil. HCl  ---> ZnCl2 + H2 (evolves) https://www.effectivegatecpm.com/niq1403wy?key=75636aaae2c528f3bfebf44b89ea916e 3. Which of the following is a Noble gas? Oxygen Nitrogen Chlorine Neon Answer: Neon Explanation: Group 8 elements are called Noble gases. Since Neon is a group 8 element it is a Noble gas 4. Formula of Bleaching Powder? CaOCl2 NaHCO3 NaOH Na2CO3 Answer: CaOCl2 Explanation: Chemical name for bleachin...

Temporary positions in NIIST TRIVANDRUM       CSIR-NIIST invites applications from candidates to be applied online for the posts of Project Assistant and Project associates on purely temporary basis.               Online application starting date : 09-10-2025       Closing date of application : 15-10-2025, 5.30 PM (Wednesday)         The vacancy details are as follows: 1. APTD-13 Project Assistant (PA-I) Number of Posts: One* Essential Qualification: B.Sc in Food Science and Technology/Food Science/Food Technology from a                                           recognized University or Equivalent Monthly Stipend: 20,000+18% HRA 2. APTD-14 Project Associate (PAT-I) Number of Posts: One* Essential Qualification: M.Sc in Biochemistry or Molecular Biology from a recognized Uni...

  CSIR UGC-NET EXAM DECEMBER 2025 PDF          National testing agency(NTA) will be conducting the joint CSIR UGC-NET Exam 2025 on the month of December for the award of JUNIOR RESEARCH FELLOW and appoinment as ASSISTANT PROFESSOR appoinment as ASSISTANT PROFESSOR and admission to ph.D and admission to PhD only through Computer mode of examination(CBT). The schedule details are given below: Online submission details  From 25 Sept 2025 to 24 Oct 2025 Date of Exam 18 December 2025 Duration of exam 3 hours (180 mins) On shift basis 09:00 AM to 12:00pm 03:00 PM TO 06:00PM Medium of exam English and Hindi Website https://csirnet.nta.nic.in/ Information bulletin link https://examinationservices.nic.in/ExamSys2026/root/Home.aspx?enc=Ei4cajBkK1gZSfgr53ImFTqGsyg38PlGNCGSuvSzsiV1qebCK8HwyoyshndJPRez https://www.revenuecpmgate.com/ttk78pwf92?key=267bf0257473f0128ce906f40f429fa9        Candidates who wish to apply may go through the i...

10 pyqs with solutions for scientific assistant for chemistry  1. Which of the following is an example of a lewis acid? 1. HCL 2. H2SO4 3. AlCl3 4. NaOH Answer: AlCl3  Explanation: Since lewis acid is a electron acceptor comparing to all other options AlCl3 only accepts electrons. 2.   Which of the following is most  acidic? 1. O- nitrophenol 2. Phenol 3. O- cresol  4. m-cresol Answer: O-nitrophenol Explanation: Since the nitro group is EWG, the proton in the OH group can easily leaves making it acidic 3.   Which of the following   properties increases from left         to right across a period in the periodic table? 1. Atomic radii 2. Ionization enthalpy  3. Atomic mass 4. Metallic conductivity    Answer: Ionization enthalpy   Explanation: Since moving   from left to right across    period the electrons can be pulled more towards the nucleus leading to inc...