Answer: A) Vacuum Explanation: A Sound wave needs a medium for propogation. Hence, Sound cannot travel through a vacuum. A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work in.

Answer: D) Rs. 1250 Explanation: 2500 in 5th year and 3000 in 7th year So in between 2 years Rs. 500 is increased => for a year 500/2 = 250So, per year it is increasing Rs.250 then in 5 years => 250 x 5 = 1250Hence, the initial amount must be 2500 - 1250 = Rs. 1250

Answer: A) Geothermal Energy Explanation: Geothermal energy is heat energy generated and stored in the Earth. Geothermal energy has been used for thousands of years in some countries for cooking and heating. It is simply power derived from the Earth's internal heat.

Answer: B) 10 Explanation: 175760 =2³ x 2 x 5 x 13³= 2³ x 2 x 5 x 13³ To make perfect cube, it must be divided by 2 x 5 = 10

Answer: C) 27.77 Explanation: If the price of the oranges decreases by 10%, the woman would save 10% of the money that is Rs.50 to buy the same amount as before.Now in Rs. 50 she can buy 2 kg more, therefore the current price of 1 kg of oranges is Rs25.Now, this current price is after 10% reduction.       Therefore, the original price =  25/0.9  = Rs. 27.77

Answer: D) 8 Explanation: 9321 = 3 x 13 x 239 = 31 x 13 1 x 239 1 ; add one to all the powers ie., (1+1) x (1+1) x (1+1)= 8 ; we get eight factors.

Answer: D) 149600 kgs Explanation: Let the total quantity of gold be p kgs. According to the question, 50% of p + 25% of p + 12.5% of p = 130900 87.5% of p = 130900 p = 130900 x 100/87.5  = 149600 kgs.   Therefore, the initial gold quantity that king has = p = 149600 kgs.

Answer: B) 76.92% Explanation: Let the milk he bought is 1000 ml Let C.P of 1000 ml is Rs. 100 Here let he is mixing K ml of water He is getting 30% profit => Now, the selling price is also Rs. 100 for 1000 ml => 100 : K% = 100 : 30 10 : 3 is ratio of milk to water => Percentage of milk = 10 x 100/13 = 1000/13 = 76.92%