Doubtly
@Doubtly · Joined Feb 2021
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- The angle of 1" (second of arc) in a radian is equal to: (1) 4.85 × 10–4 (2) 4.85 × 10–6 (3) 1.75 × 10–2 (4) 1.75 × 10–4 A minute of arc is πover 10800 of a radian. A second of arc, arcsecond (arcsec), or arc second, denoted by the symbol ″, is 1over60 of an ar... 1
- Define ionization enthalpy. Name the factors on which ionisation enthalpy depends? How does it vary down the group and across a period? Variation of ionization energy down the group: On moving down the group, the ionization enthalpy decreases. This is because the electron is... 2
- What are the valence electrons ? For s-block and p-block elements show that number of valence electrons is equal to its group number. Electrons present in the outermost shell of the atom of an element are called valence electrons. 3Li is an s-block element and its electroni... 1
- Compare chemical properties of metals and non metals. The difference in chemical properties between metals and nonmetals. Nonmetals Metals 1. Nonmetals form acidic or neutral oxides when they re... 1
- Explain : electronegativity and electron gain enthalpy. Which of the two can be measured experimentally? The ability of a covalently bonded atom to attract the shared electrons toward itself is called electronegativity (EN). Electronegativity ca... 1
- Why the elements belonging to the same group do have similar chemical properties ? Chemical properties of elements depend upon their valency.Elements belonging to the same group have the same valency. Hence, the elements be... 1
- Why the second ionization enthalpy is greater than the first ionization enthalpy ? The second ionization enthalpy (Δ_iH₂) is greater than the first ionization enthalpy (Δ_iH₁) as it involves removal of electron from the pos... 1
- Explain the screening effect with a suitable example. In a multi-electron atom, the electrons in the inner shells tend to prevent the attractive influence of the nucleus from reaching the outerm... 1
- Ionization enthalpy of Li is 520 kJ mol-1 while that of F is 1681 kJ mol-1. Explain. Both Li and F belong to period 2. Across a period, the screening effect is the same while the effective nuclear charge increases. As a resul... 1
- La belongs to group 3 while Hg belongs to group 12 and both belong to period 6 of the periodic table. La and Hg both belong to period 6. Therefore, n = 6. Elements of group 3 to group 12 belong to the d-block of the modern periodic table. The... 1
- Write an e-mail informing the office-bearers of a school’s Science Society about their meeting To: (e-mail ids of office bearers of the Science Society at Abalus Public School, Husainganj, Lucknow) Cc: (e-mail ids of other staff member... 1
- Write an E-mail addressing all students and teachers, and informing them about the fair and informing students To: (e-mail ids of students/class teachers concerned) Subject: Charity Fair is being organized for anath ashram {or any needy group of peopl... 1
- Write a request letter to your headmaster to start yoga classes in school. 207, ram nivas bhagat singh road, Dombivali, {Date here} To, The Headmaster, Subhash chandra bose Vidyalaya, dombivali (E), Thane - 421201 S... 2
- maharashtra board doubt solution for std 10th to 12th Brainiak.in is one of the best social learning platform , we help maharashtra board students to clear doubts from the syllabus , our team ex... 1
- Zr(Z=40) and Hf(Z=72) have similar atomic and ionic radii because of : (1) having similar chemical properties (2) belogning to same group (4) lanthanoid contraction ::From IV A to II B Due to lanthanoid contration size of 4d & 5d series elements of same group are approx same. 1
- Identify the compound that will react with Hinsberg's reagent to give a solid which dissolves in alkali Correct option is 4) 1º amine reacts with hinsberg reagent to give ppt. that is soluble in alkali. CH3–CH2–NH2 https://lh3.googleusercontent... 1
- The RBC deficiency is deficiency disease of: (1) Vitamin B2 (2) Vitamin B12 (3) Vitamin B6 (4) Vitamin B1 Correct option is 2) Vitamin B12 2
- Which one of the following polymers is prepared by addition polymerisation? (1) Dacron (2) Teflon (3) Nylon-66 (4) Novolac Teflon:: Correct Answer is 2) Teflon 2