That 8 letter word is Whatsapp (a messenger app) First four letters:   WHAT a question Letters 2,3,4:     HAT protects our headLetters 5,6,7:   SAP an IT companyLetters 7,8:    PP same.

Answer: D) Refraction of light & Total Internal Reflection of light Explanation: A Mirage is a naturally occurring optical phenomenon in which light rays bend to produce a displaced image of distant objects or the sky. It is caused due to Total internal Reflection. It is an optical illusion observed in deserts or hot summer days due to which a person sees a pond of water some distance ahead of him in which the surrounding objects appear inverted. How Mirage Forms:: 1. The temperature of other layers of atmosphere goes on decreasing as we go up.2. Therefore density and refractive index of air changes as one goes up.3. Thus a ray of light,gets refracted more and more away from the normal.4. At a particular angle when a ray of light exceeds critical angle, total internal reflection takes place and ray of light gets reflected in the same medium.5. when the reflected ray reaches our eye, it appears as coming from tree or sky .6. Hence the inverted image of tree creates an impression from a pond of water.

Answer: B) 7/15 Explanation: Given total students in the class = 60Students who are taking Economics = 24 andStudents who are taking Calculus = 32Students who are taking both subjects = 60-(24 + 32) = 60 - 56 = 4Students who are taking calculus only = 32 - 4 = 28probability that a randomly chosen student from this group is taking only the Calculus class = 28/60 = 7/15.

Answer: C) 71 Explanation: To find the greatest number which divides the numbers 964, 1238 and 1400 leaving the remainders 41, 31 and 51 is nothing but the HCF of (964 - 41), (1238 - 31), (1400 - 51). Therefore, HCF of 923, 1207 and 1349 is 71.

Answer: A) 14.28 % profit Explanation: Let 1kg of Rs. 100 then 840gm is of Rs. 84.Now (label on can 1kg but contains 840kg ) so for customer it is of Rs. 100 and further gives 4% discount [he sells his article on 4% loss on cost price.] So now S.P = Rs. 96But actually it contains 840 gm so C.P for shopkeeper = Rs. 84S.P = Rs. 96C.P = Rs. 84Profit% = {(S.P-C.P)/C.P}x100{(96-84)/84} x 100 = 14.28571429% PROFIT.

Answer: A) 12 Explanation: We have 12 months.   In every month we get 28 or more days.    So that implies we get 28 days in each and every month.

Answer: C) Window Explanation: The Opening in a wall to let in air or light is nothing but a Window.

Answer: B) Gold Explanation: Here in the given options, Gold is a malleable substance. Malleable substance means a metal or a material able to be hammered or pressed into shape without breaking or cracking. i.e, tensile.