Doubtly
@Doubtly · Joined Feb 2021
- Answers
- 3,792
- Questions
- 4,033
- Upvotes received
- 424
- H. Which properties of solvents are useful for solvent extraction? Organic compound must be more soluble in the organic solvent, than in water. Solvent should be immiscible with water and be able to form two... 1
- G. Give names of two materials used as stationary phase in chromatography. names of two materials used as stationary phase in chromatography. alumina silica gel 1
- F. What will happen if the upper outlet of the condenser is connected to the tap instead of the lower outlet? It is necessary to cool the condenser with cool water for proper functioning of condenser. If tap is connected to the upper outlet then jack... 2
- Identify the pair whose dimensions are equal The correct option is B. The dimensions of torque and work are equal. Both have dimensions as [ML²T⁻²] Explaination: Work (W) = F.s = Fs cos... 1
- Which of the following physical quantities is an axial vector? Correct option is d) Torque Concept :: Axial vectors are those vectors that represent rotational effect and act along the axis of rotation.... 1
- A rocket is fired vertically with a speed of 5 kms-1 from the earth’s surface. How far from the earth does the rocket go before returning to the earth The correct option is (a) 8.0 ×10⁶ m Video Explaination From physics galaxy https://youtu.be/nz4kjm8L6ZU This video not belong to Brainiak f... 1
- The position vector of a moving particle at time t is r=3i+4t^2j-t^3k .. Its displacement during the time interval t=1 s to t=3 s is Correct answer is 32j-26k Explaination:: r=3i+4t²j-t³k r_(t=1s)=3i+4j-k r_(t=3s)=3i+36j-27k Displacement = (r_(t=3s))-(r_(t=1s)) = 32j-26k 1
- If a unit vector is represented by 0.5i +0.8 j +ck then the value of 'c' is Correct option is b) √(0.11) Explaination:: The unit vector is given as A=0.5i +0.8 j +ck Magnitude of unit vector is always equal to 1 √((0... 1
- The area of the region bounded by the curve y = 2x – x2 and x – axis is Correct answer is 4/3sq.units Explaination:: Given curve is y =2 x-x² or (x-1)² =-(y-1) The curve cut the x -axis at (0,0) and (2,0) . there... 1
- If r.v. X : waiting time in minutes for bus and p.d.f. of X is given by The correct answer is option b) 0.8 f(x)= \1/5,/0, \ \ 0≤ x≤ 5, /otherwise, Solution will come soon 1
- The sum of two numbers is 128 and their difference is 16. Find the numbers. Let the two numbers be x and y According to 1^st condition , x+y=128 ------1 According to 2nd condition , x-y=16 --------2 Adding equation 1... 1
- 5 Chairs and 4 Tables Together Cost ₹5600, While 4 Chairs and 3 Tables Together Cost ₹ 4340. Find the Cost of Each Chair and that of Each Table Video solution:: https://youtu.be/mG1XSNDtBig Text Solution Let the cost of a chair be ₹ x and that of a table be ₹ y, then 5x + 4y = 5600 …... 1
- 5 books and 7 pens together cost Rs 79 whereas 7 books and 5 pens together cost Rs 77, find the total cost of 1 book and 2 pens. Let the cost of a book be Rs x and that of a pen be Rs y. Then, 5x + 7y = 79 .....(i) 7x + 5y = 77 ....(iii) Multiplying equation (i) by 5 a... 1
- Uncertainty in position of a particle of 25 g in space is 10–5 m. Hence, uncertainty in velocity (m s–1) is (Planck’s constant, h = 6.6 × 10–34 Js) Correct option is (a) 2.1 × 10^(–28) Explaination:: mass=25g=25 × 10⁻³ kg , Δx=10⁻⁵m According to Heisenberg uncertainty principle triangle... 1
- Which of the following ions has the maximum magnetic moment ? Correct option is (a) Mn²⁺ Explaination ::: number of unpaired electrons in Mn²⁺ =5 number of unpaired electrons in Fe²⁺ =4 number of unpair... 1
- Energy of H-atom in the ground state is –13.6 eV, hence energy in the second excited state is Correct answer is option (c) –1.51 eV Explaination:: 2 ^nd\ excited \ state \ n=3 E n =− 13.06/n² -By formula E₃=-13.06/3²=-13.06/9 = -1.51... 1
- Identify from the following reactions the reactants that undergo oxidation and reduction A. Fe + S → FeS Here , Fe is oxidised from 0 to +2, while S is reduced from 0 to -2 Fe undergoes oxidation (as losing electrons) Sulphur und... 1
- a.When the gas formed on heating limestone is passed through freshly prepared lime water, the lime water turns milky i. When limestone (CaCO₃) is heated; it undergoes decomposition reaction giving calcium oxide (CaO) and carbon dioxide (CO₂) as products. ii... 1