Doubtly
@Doubtly · Joined Feb 2021
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- The green house gas/es is (are : (A) Carbon dioxide (B) Oxygen (C) Water vapour (D) Methane (1) (A), (C) and (D) only The green house gases are CO_(2 ), H₂O(vapour) & CH₄ 1
- The equivalents of ethylene diamine required to replace the neutral ligands from the coordination 2 is the correct answer for this question [Co(NH₃)₄Cl₂]Cl + 2en → [Co(en)₂Cl₂]Cl + 4NH₃ 1
- Complete combustion of 750 g of an organic compound provides 420 g of CO2 and 210 g of H2O. 3 is the answer . This is a Liebeig method for estimation of carbon and H-percentage % of H-element . 1
- A certain element crystallises in a bcc lattice of unit cell edge, length 27ºÅ. If the same element Answer: 33 Explanation:: for bcc structure 4r=sqrt3a r=sqrt3aover4 …1 For FCC structure 4r=sqrt2a r=sqrt2aover4 …2 From 1 and 2 1
- The type pollution that gets increased during the day time and in the presence of O3 is : (2) Oxidising smog In presence of ozone(O3), oxidising smog gets increased during the day time because automobiles and factories produce mai... 1
- Which of the following reaction DOES NOT involve Hoffmann bromamide degradation ? The correct answer is option 3) This reaction does not involve haffmann bromanide degradation Rest all options involve haffmann bromamide de... 1
- The process that involves the removal of sulphur from the ores is : jee main march 2021 1) roasting Removal of sulphur from the ore is done by Roasting. 1
- Which among the following pairs of Vitamins is stored in our body relatively for longer duration ? (2) Vitamin A and Vitamin D 2
- In chromatography technique, the purification of compound is independent of : Correct answer is option (2) Physical state of the pure compound In chromotography technique, the purification of a compound is independent... 1
- Which of the following is Lindlar catalyst ? (1) Cold dilute solution of KMnO4 (2) Partially deactivated palladised charcoal 2
- In thermodynamics, heat and work are : (1) Extensive thermodynamic state variables (2) Point functions (3) Path functions The correct answer is option 3) path function 2
- One main scale division of a vernier callipers is 'a' cm and nth division of the vernier scale coincide with (n – 1)th The correct answer is option D) 10aover n Explanation:: 1
- A 25 m long, antenna is mounted on an antenna tower. The height of the antenna tower is 75 m. The correct answer is option 3) 100 m Explanation: height of antenna= λover 4 25= λover 4 λ=100 1
- The maximum and minimum distances of comet from the Sun are 1.6 × 1012 m and 8.0 × 1010 m respectively The correct answer is option A) 3.0×10³ m/s Explanation:: L=mv₁r₁=mv₂r₂ V₂= v₁r₁over r₂ =v₁ 8×10¹⁰over 160×10¹⁰ =6×10⁴over 20 =3000 m/s 1
- 22 Ne nucleus, after absorbing energy, decays into two α-particles and an unknown nucleus. The unknown nucleus is The correct answer is option B) carbon Explanation:: ²²Ne decays α particle = He²⁺ Mass No = 4 p=2,n=2 So, New mass no. =22−8=14 Atomic No.... 1
- Which of the following statement(s) is (are) correct ? (A) The rest mass of a stable nucleus is less than the The correct answer is option A ) The rest mass of a stable nucleus is less than the sum of the rest masses of its separated nucleons. 2
- The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statements is true? The correct answer is option A) Its kinetic energy increases and its potential and total energies decrease. 1
- Photoelectrons are emitted when 400 nm radiation is incident on a surface of work function 1.9eV. =-54.4 eV, -13.6 eV, -6.04 eV, -3.4 eV, -2.176 ev, -1.51 eV Difference of energies lying between 2 and 4 eV is -3.4+6.04=2.64 eV -2.176+6.04... 2