Answer: D) Euclid Explanation: Euclid of Alexandria was a Greek mathematician, often referred to as the Father of Geometry.

Answer: D) 18 hrs Explanation: From the given data, 18 snakes can eat 18 bananas in 18 hrs. => 1 snake can eat 1 banana in 18 hrs => 79 snakes can eat 79 bananas in 18 hrs.   Hence, 18 hrs.

Answer: A) line segment Explanation: As parabola is a locus of a point, which moves so that its distance from focus and directrix is always equal.   The latus rectum of a conic section is the chord (line segment) that passes through the focus, is perpendicular to the major axis and has both endpoints on the curve. The length of the latus rectum is determined differently for each conic.                                          The length of a parabola's latus rectum is 4p, where p is the distance from the focus to the vertex.

Answer: C) Increase in font size Explanation: CTRL + ] is a computer shortcut and is used for Increase in font size.   Shortcuts : Re-do ---- Ctrl + Y Right align text ---- Ctrl + R Expand or collapse the ribbon ---- Ctrl + F1

Answer: D) Covalent- network Explanation: Graphite is a covalent-network type of crystalline solid.   There are two main categories of solids. 1. Crystalline solids and 2. Amorphous solids. Crystalline solids are those in which the atoms, ions, or molecules that make up the solid exist in a regular, well-defined arrangement. There are four types of crystalline solids : Ionic solids :— Made up of positive and negative ions and held together by electrostatic attractions. They’re characterized by very high melting points and brittleness and are poor conductors in the solid state. An example of an ionic solid is table salt, NaCl. Molecular solids :— Made up of atoms or molecules held together by London dispersion forces, dipole-dipole forces, or hydrogen bonds. Characterized by low melting points and flexibility and are poor conductors. An example of a molecular solid is sucrose. Covalent-network (also called atomic) solids :— Made up of atoms connected by covalent bonds; the intermolecular forces are covalent bonds as well. Characterized as being very hard with very high melting points and being poor conductors. Examples of this type of solid are diamond and graphite, and the fullerenes. As you can see below, graphite has only 2-D hexagonal structure and therefore is not hard like diamond. The sheets of graphite are held together by only weak London forces! Metallic solids :— Made up of metal atoms that are held together by metallic bonds. Characterized by high melting points, can range from soft and malleable to very hard, and are good conductors of electricity.

Answer: A) Biosphere Explanation: A biosphere is the sum of all the ecosystems established on planet Earth. An ecosystem is an area in which the plants and animals all interact to create a living environment. Therefore ecosystem is a smaller unit of earth, all ecosystems together form the earth.

Answer: D) 4.3 light-years away Explanation: The nearest stars to Earth are in the Alpha Centauri triple-star system, about 4.37 light-years away. One of these stars, Proxima Centauri, is slightly closer, at 4.26 light-years.   Of all the stars closer than 15 light-years, only two are spectral type G, similar to our sun: Alpha Centauri A and Tau Ceti. The majority are M-type red dwarf stars.   Only nine of the stars in this area is bright enough to be seen by the naked human eye from Earth. These brightest stars include Alpha Centauri A and B, Sirius A, Epsilon Eridani, Procyon, 61 Cygni A and B, Epsilon Indi A and Tau Ceti.

Answer: D) Shadow Explanation: