Student E Knowledge

Given below are some very important long answer type questions to prepare for CBSE Class 10 Science Exam 2020: Question 1.  (a) Write chemical equations for the reactions involved in obtaining pure alumina  from the mineral bauxite which has impurities of iron oxide and silica. (b) Draw a labelled diagram of the electrolytic tank cell used for the extraction of aluminium from alumina. Answer. The reaction involved in obtaining pure alumina from the mineral bauxite having impurities of iron oxide and silica is: The iron oxide and silica (sand) present in the bauxite ore do not dissolve in sodium hydroxide solution. Therefore, they are separated by filtration. CBSE Class 10 Science Previous Years' Solved Question Papers (b) Given below is the labelled diagram of the electrolytic tank cell used for the extraction of aluminium from alumina: Question 2.  (a) What are ‘magnetic field lines’? How is the direction of a magnetic field at a point deter...

Vectors and Three Dimensional Geometry Formulas for Class 12 Position Vector O P − → − = r ⃗  = x 2 + y 2 + z 2 − − − − − − − − − − √ Direction Ratios l = a r , m = m r , n = c r Vector Addition P Q → + Q R → = P R → Properties of Vector Addition C o m m u t a t i v e P r o p e r t y a ⃗  + b ⃗  = b ⃗  + a ⃗  A s s o c i a t i v e P r o p e r t y ( a ⃗  + b ⃗  ) c ⃗  + = a ⃗  + ( b ⃗  + c ⃗  ) Vector Joining Two Points P 1 P 2 − → − − = O P 1 − → − − O P 1 − → − Skew Lines C o s θ = ∣ ∣ ∣ a 1 a 2 + b 1 b 2 + c 1 c 2 a 2 1 + a 2 1 + c 2 1 √ a 2 2 + a 2 2 + c 2 2 √ ∣ ∣ ∣ Equation of a Line x − x 1 a = y − y 1 b = z − z 1 c Algebra Formulas For Class 12 If a ⃗  = x i ^ + y j ^ + z k ^  then magnitude or length or norm or absolute value of  a ⃗   is  ∣ ∣ a → ∣ ∣ = a = x 2 + y 2 + z 2 − − − − − − − − − − √ A vector of unit magnitude is unit vector. If  a ⃗   is a vector then unit vector of...