153+(-302)

= 153 - 302

= - 149

Time is a concept which is related to our perception of reality. There are three times: past, present and future. Tense is a grammatical category which is marked by verb inflection and expresses when an event or action happens in the flow of time.

The king was told that in order to decide the right time for doing something, it was necessary to look into the future. Since only magicians could do so, he was advised to go to magicians.

(−1,−7), (−2,−6), (−3,−5), (−4,−4), (−5,−3), (−6,−2), (−7,−1)

Small finger-like projections found in our small intestine are known as villi. The function of the villi is to increase the surface area of the intestine so as to increase its capacity to absorb nutrients and liquid from food passing through it.

Digestion of food in human beings begins in the mouth. The mouth cavity contains teeth, tongue and salivary glands. The teeth cut the food into small pieces, chew and grind it. This is called physical digestion. Salivary glands produce saliva which mixes with the food. This involves chemical digestion of food. The saliva contains an enzyme called salivary amylase which digests the starch and converts it into maltose sugar.

Rhizobium is a nitrogen fixing bacteria. Elemental nitrogen cannot be used directly by plant or animals . They need to be converted in usable Nitrogen source like nitrites and nitrates.
Rhizobium convert elemental nitrogen to nitrate .nitrates are taken up by leguminous plant .at the same time leguminous plant provide nutrient to rhizobium.

Neutralisation Reaction: The reaction in which an acid reacts with a base to form salts and water is called neutralization reaction.

Acid + base                    Salt + Water

Some heat is always evolved in a neutralization reaction.  The heat raises the temperature of reaction mixture due to which the reaction mixture becomes hot. In this reaction two new substances salt and water are formed.

Temperature is a measure of the average kinetic energy of all the particles making up a substance. Temperature does not depend upon the mass of an object. The thermal energy of a substance is a measure of the total kinetic energy of its particles.
The difference between temperature and thermal energy is that temperature measures the average kinetic speed of molecules and thermal energy is the total kinetic energy of all particles in a given substance. Both temperature and thermal energy are made by the movement of particles.

Pencil lead is made of graphite. Telephones have copper wiring. Carpets in our homes contain sulphur and chromite. Clocks are made of Quartz and Pentlandite.

• Amoeba is a microscopic single-celled organism found in pond water which has a cell membrane, a round, dense nucleus and many bubble like vacuoles.
• The shape of amoeba is variable.
• It has tiny finger like projections called pseudopodia or false feet for movement and capture of food.
• It eats tiny organisms by spreading out its pseudopodia around its food particle and then engulfing it.
• The food gets trapped inside food vacuole, into which digestive juices are secreted and convert them into simpler substances.
• The digested food is then absorbed which is required for growth, maintenance and multiplication.
• The undigested food is expelled out by vacuole.

In all mammals, the salivary glands functions as an exocrine gland, which produces saliva through a system of ducts. Among all other mammals, humans have hundreds of salivary glands and are present within the mouth. The basic secretion units of salivary glands are called acini and are composed of clusters of cells. 

Salivary Glands are composed of two types of secretory cells: 

1. Serous cells– These cells are present on the surface of epithelium, submucosal glands and secretes an enzyme solution.
2. Mucous cells– These cells are present inside the stomach, in the necks of the gastric pits and produces mucus.

-(20) × (-4) × (-2)

= -(20)× 8

= -160

Following are three important differences between democracy and dictatorship:

• Democracy is based on the idea of deliberation and negotiation. As a result, democratic political systems take time in executing decisions. Dictatorships, on the other hand, need not bother themselves with public opinion, and hence, decision making process in such systems is quicker and efficient.
• In a democracy, decisions of the Government are acceptable to the people and are more effective in redressal of the public’s concerns. Dictators can take decisions that are not acceptable to the public at large.
• A democratic government has a legitimacy attached to it since it is voted for by the general mass, and thus it has the sanction to rule. A dictatorship has no public sanction as such. It is a result of monarchical rule or a coup.

The addition follows associative property i.e. regardless of how numbers are parenthesized the final sum of the numbers will be same. Associative property of addition states that:

(x+y)+z = x+(y+z)

Let us say, we want to add 5+10+4. It can be seen that the answer is 19. Now, let us group the numbers; put 5 and 10 in the bracket. We get,

⇒ (5+10)+4 = 15+4 = 19        (Remember BODMAS rule)

Rule for the associative property of multiplication is:

(xy) z = x (yz)

On solving 5×3×2, we get 30 as product. Now as in addition, let’s group the terms:

⇒ (5 × 3) × 2 = 15 × 2 = 30         (BODMAS rule)