Answer: A) Limestone Explanation: Karst is a type of landscape that is characterized by caverns, caves, sinkholes, and underground streams. These features were all caused by erosion of the underlying rock.   Limestone type of rock usually underlies a karst landscape.

Answer: B) On a cloudless night, I studied Pisces, a constellation in the North sky. Explanation:

Answer: A) the existence of unpaired electrons in the valence shell Explanation: When atoms react they do so in order to reach the lowest energy, which is the most stable. The electrons orbitals will overlap in the way that reduces the energy the most. Orbitals of similar energy will produce the greatest stabilisation.The answer you gave isn't the whole story, it depends what species is reacting with what. The effective nuclear charge on the atom will affect the energy of the valance electrons.   Hence, the reactivity of an atom arises from the existence of unpaired electrons in the valence shell.

Answer: A) To add interactivity to HTML Pages. Explanation:

Answer: C) Stamps Explanation: Stamps are what travel around the worldstaying in one spot. Slippers and walking stick can also travel around the world but they will not stay at one spot. So they are eliminated.

Answer: B) Joseph A. Schumpeter Explanation: Entrepreneurship as a theory of business was propounded by Joseph. A. Schumpeter.   Schumpeter’s Innovation Theory of Profit : Definition:  The Innovation Theory of Profit was proposed by Joseph. A. Schumpeter, who believed that an entrepreneur can earn economic profits by introducing successful innovations.

Answer: A) 0.5 Explanation: In mathematics, a geometric progression, also known as a geometric sequence, is a sequence of numbers where each term after the first is found by multiplying the previous one by a fixed, non-zero number called the common ratio.   Herein the given sequence, 4, 2, 1, 0.5, 0.25, 0.125,... Common Ratio r = 2/4 = 1/2 = 0.5/1 = 0.25/0.5 = 0.125/0.25 == 0.5.

Answer: D) 100000 ohm Explanation: Under dry conditions, the resistance offered by the human body may be as high as 100,000(10^5) Ohms.   Depending on the person, a rough value for the internal resistance of the human body is 300-1,000 Ohms. The skin's resistance is much lower if it is wet or burnt/blistered. There are a lot of factors involved and not every person has the same electrical resistance. For instance, men tend to have lower resistance than women. Within the body, the tissues with the greatest resistance are bone and fat - nerves and muscle have the least resistance.