Answer: D) All the above Explanation: A pure substance can be defined as any single type of material that has not been contaminated by another substance. In chemistry, a pure substance has a definite composition. It can be a compound or an element. A pure substance is considered to be a material that consists of one type of "building block" of matter. Examples of pure substances include tin, sulfur, diamond, water, pure sugar (sucrose), table salt (sodium chloride) and baking soda (sodium bicarbonate). Tin, sulfur, and diamond are examples of pure substances which are chemical elements. All elements are pure substances. Water, sugar, salt and baking soda are pure substances which are chemical compounds. Chemical compounds also are pure substances

Answer: C) 2.83 kmph Explanation: Given speed of the person = 8 1/2 = 17/2 kmphLet the speed of the stream = x kmphspeed of upstream = 17/2 - xspeed of downstream = 17/2 + xBut given that,2(17/2 - x) = 17/2 + x=> 3x = 17/2=> x = 2.83 kmph.

Answer: B) 4 yrs Explanation: Let the present age of Deepa = 5p Let the present age of Hyma = 6p After four years their ratio = 6 : 7 => 5p + 46p + 4 = 67 => 35p + 28 = 36p + 24 => p = 4 Therefore, the difference between their ages = 24 - 20 = 4 years.

Answer: C) 10^7 ergs Explanation: 1 Joule = 107 ergs = 0.000239 Kilo Calories. Joule is the Unit of Energy. Joule is equal to Energy transferred to an object when a force of One Newton acts on that object in the direction of its motion through a distance of one metre.(1 N-m)

A Lobster is one which goes black in water and comes out red.

A Contact force is a force applied to a body by another body that is in contact with it. Contact force acts on a point of direct contact between the two objects. This force can either be continuous as a continuous force or can be momentary in the form of an impulse. Contact force is governed by Newton’s Laws. Examples :: Contact force is responsible for most of the interactions we experience in the daily life. 1. Writing your name with a pen, pushing a car up a hill, lifting an object, etc... 2. Kicking a ball, hammering a nail, etc... are some of the everyday examples where contact forces are at work. In the first case, the force is continuously applied by the person on the car or pen or an object while in the second case the force is delivered in a short impulse.   Contact forces are often decomposed into orthogonal components one perpendicular to the surface in contact called the normal force, and one parallel to the surface in contact, called the friction force.

Answer: D) 91 Explanation: Here in the given numbers 91 is a Composite number. Since it has factors of 7 and 13 other than 1 and itself.   Composite Numbers : A composite number is a positive integer which is not prime (i.e., which has factors other than 1 and itself). Examples :: 4, 6, 8, 12, 14, 15, 18, 20, ...

Answer: B) FALSE Explanation: No, the given statement is False. Parasites are organisms that feed on other organisms causing harm to them. Foods that allow micro organisms to grow are called Growth Mediums.