Life in tropical rainforests

The tropical rainforests are the wet, warm forests of trees that grow very closely together. The canopy (tallest tress) in the rainforest can release 200 gallons of water each year into the atmosphere. The resulting moisture hangs over the forest, keeping the interior warm and humid. Animals living in the rainforest have had to adapt to these wet, warm conditions and have had to find niches that allow them to thrive. They do this by altering species characteristics to fit the tall trees, the constant humidity and the quiet rainforest floor. Monkeys, apes, gorillas, elephants, tigers, lions, lizards snakes, birds, insects are the major type of animals found in these regions. Let's discuss the characteristics of some animals found in tropical regions in detail.
Adaptations of a Lion and Tiger
Lion and tigers are the wild animals and generally found in forests. They have following features which help them to survive in their environment.

• The golden brown fur of lion and dark vertical stripes on reddish-orange fur with a lighter underside on tiger's body help them to blend into their surroundings. It helps them to camouflage and also helps them to catch their prey.
• Their powerful hind legs help them run fast so they can catch their prey.
• The thick mane of lion helps male lion look bigger and also it protects the throat.
• They use their claws to rip and tear prey's flesh and meat.
• They have eyes in front which allow for depth perception and ability to judge distances when stalking or ambushing prey.
• Their sharp sense of smell also helps them to locate their prey..
• They have sharp teeth for eating other animals.

Adaptations in Elephants

• The most distinctive feature of elephant is its trunk. The trunk helps the elephant to pick up food and puts into its mouth, for drinking water.
• The elephant has a strong sense of smell because it uses its trunk as a nose.
• Elephant has big and long pointed teeth called tusks which come out from its closed mouth. They use this to tear off the bark of trees, which it eats as food..They also use this for fighting with their enemies and protecting themselves.
• The elephants has large ears which help them to hear even very soft sound.

Adaptations in a Monkey
Monkeys are adapted for tree-climbing lifestyle. They have following adaptations that help them to live on trees.

• They have forward-looking eyes that enable them see distances below from great heights.
• They also have hands and feet that allow them to grip on trees as well as opposite-matching fingers and toes that allow them to wrap their hands or feet around objects or tree branches for a firm grip. This ability allows them to be agile and to avoid predators.
• The highly developed brains of monkeys allows them to make mental maps of food locations and knowing when the fruits will be ripe and therefore ready for food.
• They also are able to grip food with their hands like humans. Some monkeys also have special tails that serve as a fifth limb when gripping food.

Adaptations in a lion-tailed Macaques

• The body of a lion-tailed macaque is covered with long, black hairs. They have silvery manes grown around their faces grow and also have balls of fur at the tips of their tails. These characteristics give them somewhat similar characteristics to lions.
• Lion-tailed macaques spend majority of their lives in the treetops where they will find food and safety. Their diet consists of fruits, nuts, seeds, leaves and insects. They are good climbers and only come down when they do not find food.

New World monkeys
These are small to mid-sized primates, ranging from 16 cm to 70 cm in length. Their weight varies from 190 g to 15 kg. Their noses are flatter and they have side-facing nostrils.

Questions Based on Some Basic Concepts

Practice Question
 
1. Which of the following method/methods of expressing concentrations is/are independent of temperature?
    (a)  Mole fraction   (b) Molarity   (c)  Normality    (d)  Molality

2.  80 g of oxygen contain as many atoms as in
    (a)  10 g of hydrogen  (b) 5 g of hydrogen   (c)  80 g of hydrogen    (d)  1 g of hydrogen

3.  What is the molality of pure water?
    (a)  1    (b)   18   (c)  55.5    (d) None of these

4.  Which of the following methods of expressing concentration varies with temperature?
    (a)  Molality    (b)  Weight per cent  (c)  Normality     (d)  Molarity

5. The following substances are present in different containers   
     (i)     One gram atom of nitrogen   
    (ii)     One mole of calcium
    (iii)    One atom of silver   
    (iv)    One mole of oxygen molecules
    (v)     1023 atoms of carbon and   
    (vi)     One gram of iron
    The correct order of increasing masses (in grams) is/are:
    (a)    (iii) < (vi) < (i) < (v)    (b)    (iii) < (vi) < (iv) < (ii)
    (c)    (vi) < (v) < (i) < (iv)    (d)    (iii) < (ii) < (v) < (iv)

6.  In MgSO4 (at. mass : Mg = 24, S = 32, O = 16), the mass percentage of
    (a)    Mg = 80%    (b)    Mg = 20%
    (c)    S = 26.7%    (d)    S = 53.3%

Water

Availability of water on earth

We know that 71% of the earth is covered with water. Despite of the huge availability of water on the earth, the useful water is very less in amount. 97 percent of the water on the earth is salt water. However, only three percent is fresh water; slightly over two thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground as surface water or in the air. From the available fresh surface water 87% is found in lakes, 11% in swamps and 2% in rivers. You can see the distribution of fresh water in diagram shown below:

Do you have ever think that how much water we use in agricultural, industrial, household, recreational and environmental activities? Another interesting point of discussion is that the majority of human uses require fresh water and whether such a small amount of fresh water is sufficient to fulfill the needs of all people on the earth or not?

States of water

Water is known to exist in three different states; as a solid, liquid or gas. Liquid water is found in many places. You see liquid water coming out of the faucet, when it rains, and running in a river. Pure liquid water is free of salt, rocks, soil, and garbage. Ice, snow, and frost are examples of water in the solid state. Other examples of solid water are ice cubes, icicles, ice on a skating rink. Water in the liquid state may change to water in the gaseous state. Water evaporates to turn into a gas. Gases are colorless and odorless. You don't see anything because gas is invisible but sometimes you can hear it and smell it.

Water cycle

The water cycle is the journey of water from the land to the sky and back again on the land. The Sun's heat provides energy to evaporate water from the Earth's surface (oceans, lakes, etc.). Plants also lose water to the air by the process of transpiration. The water vapor eventually condenses, forming tiny droplets in clouds. Water vapor condenses into millions of tiny droplets that form clouds. Clouds lose their water as rain or snow, which is called precipitation. Precipitation is either absorbed into the ground or runs off into rivers. Some of the precipitation soaks into the ground. Some of the underground water is trapped between rock or clay layers; this is called groundwater. Water that was absorbed into the ground is taken up by plants. Plants lose water from their surfaces as vapor back into the atmosphere. Water that runs off into rivers flows into ponds, lakes, or oceans eventually returning to the seas as slightly salty water, where it evaporates back into the atmosphere. In this way, the cycle continues.

Sources of water

The main sources of water on the earth can be categorised as follows:
Rain, oceans, rivers, lakes, streams, ponds and springs are natural sources of water. Dams, wells, tube wells, hand-pumps, canals, etc, are man-made sources of water.
Rain water: Rain is the most important source of water on the earth. It replenishes the sources of surface water like rivers, ponds, oceans etc. It is the purest form of water but gets polluted as it comes down to the earth. Rain water collects on the earth in the form of surface water and underground water.
Surface water: The water present on the surface of the earth in the form of oceans, rivers, lakes, ponds and streams is called surface water. Surface water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, evapotranspiration and sub-surface seepage. The water in rivers and lakes comes from rain and melting of snow on mountains. Rivers flow into the sea. The water in rivers, lake and streams contains dissolved salts and suspended impurities. Water from such sources can be consumed directly or after simple treatments. On the other hand, the water in seas and oceans is salty and contain lots of dissolved salts due to which it is unfit for the consumption as drinking water.
Underground Water: Some of the rainwater seeps through the soil on to the non-porous rocks below. This is underground water. The process of seeping of rainwater into the ground is called infiltration. Sometimes due to high pressure, this water sprouts out in the form of springs. It can be obtained by digging wells, sinking tube wells, etc. Typically, groundwater is thought of as liquid water flowing through shallow aquifers, but technically it can also include soil moisture, permafrost (frozen soil), immobile water in very low permeability bedrock, and deep geothermal water.
Frozen water: It is the water present on earth in the form of icebergs and glaciers. Several schemes have been proposed to make use of icebergs as a water source, however to date this has only been done for novelty purposes. Glacier runoff is considered to be surface water.

Crystallisation

The formation of solid crystals from a homogeneous or uniform solution is called crystallisation. It is generally used to separate a solid that has dissolved in a liquid and made a solution. For crystallization to take place, a solution must be “supersaturated”, a state in which the liquid or solvent contains more dissolved solute than can ordinarily be retained at that temperature.
 
Substances like sugar, salt, urea, copper sulphate form crystals. The solution is warmed in an open container, allowing the solvent to evaporate, leaving a saturated solution. A solution that has as much solid dissolved in it as it can possibly contain is called a saturated solution. As the saturated solution is allowed to cool, the solid will come out of the solution and crystals will start to grow. The crystals can then be collected and allowed to dry. A solid that does not dissolve in a liquid can be separated by filtration. Crystallisation is a physical change as the substance undergoes crystallisation retains its chemical properties.
 
The size of crystals depends on the rate of cooling. Fast cooling will result in a large number of small crystals. Slow cooling will result in a smaller number of large crystals. Lets perform an activity to observe how crystals can be grown.

Multiple Choice Qusetions on Sulphur Dioxide (in HIndi)

1. निम्न में से कौन सा/से गुण सल्फर डाई ऑक्साइड गैस प्रदर्शित करती है?

(i) तीक्षण गंध

(ii) रंगहीन

(iii) जल में विलेयता

(iv) वायु से भारी होना
(क) केवल (i)
(ख) (ii) और (iii) दोनों
(ग) (iii) और (iv) दोनों
(घ) (i), (ii), (iii) और (iv) सभी
2. निम्न में से कौन सा कथन सही है?
(क) अमोनिया गैस जलने में सहायक है।  
(ख) अमोनिया गैस आक्सीजन की उपस्थिति में नहीं जलती।
(ग) अमोनिया गैस का उपयोग अश्रु गैस बनाने के लिए किया जाता है।  
(घ) रक्त तप्त कॉपर आक्साइड पर अमोनिया गैस प्रवाहित करने पर संकर लवण बनता है।

 3. निम्न में से किसके उपयोग से रेशम और ऊन का विरंजन किया जा सकता है?
(क) सल्फर का
(ख) सल्फर डाई ऑक्साइड का
(ग) अमोनिया का
(घ) मैग्नीशियम का
4. पौटेशियम परमैंगनेट के अम्लीय विलयन में सल्फर डाई ऑक्साइड गैस प्रवाहित करने पर यह विलयन  
(क) पीले रंग का हो जाता है
(ख) रंगहीन हो जाता है
(ग) लाल रंग का हो जाता है
(घ) हरे रंग का हो जाता है
5. सल्फर डाई ऑक्साइड गैस के लिए इनमें से कौन सा कथन सही नहीं है?
(क) 1 आयतन जल में 438 आयतन सल्फर डाई ऑक्साइड गैस घुलती है।
(ख) यह फैरिक लवण को फैरस लवण में अपचयित करती है।
(ग) यह नमी की उपस्थिति में रंगीन फूलों का रंग उड़ा देती है।
(घ) इसका उपयोग चीनी को शुद्ध करने में भी होता है।
6. निम्न में से कौन सा निर्जलीकारक नहीं है?

(क) CaCl₂
(ख) NH₃
(ग) P₄O₁₀
(घ) H₂SO₄
7. अमोनिया के विषय में निम्न में से कौन सा कथन सही नहीं है?

(क) प्रीस्टले ने चूने और नौसादर के मिश्रण को गर्म करके अमोनिया का निर्माण किया था।
(ख) यह अल्पमात्रा में वायु तथा जल में उपस्थित होती है।  
(ग) यह वायु से हल्की होती है।
(घ) यह गैस गीले नीले लिटमस को लाल कर देती है।

8. निम्न में से किस अभिक्रिया में अमोनिया गैस बनती है?

(i) कैल्शियम सायनामाइड पर भाप की अभिक्रिया से

(ii) सोडालाइम के साथ यूरिया को गर्म करने पर

(iii) अमोनियम लवण को किसी अम्ल के साथ गर्म करने पर

(iv) मैग्नीशियम नाइट्राइड की जल से अभिक्रिया के द्वारा
(क) (i) और (iii) दोनों
(ख) (iii) और (iv) दोनों
(ग) (i), (ii) और (iv) तीनों
(घ) (i), (ii), (iii) और (iv) सभी

 

उत्तरावली
1. (घ) (i), (ii), (iii) और (iv) सभी
2. (घ) [Ag(NH₃)₂]Cl
3. (ख) सल्फर डाई ऑक्साइड का
4. (ख) रंगहीन हो जाता है
5. (क) 1 आयतन जल में 438 आयतन सल्फर डाई ऑक्साइड गैस घुलती है।
6. (ख) NH₃
7. (घ) यह गैस गीले नीले लिटमस को लाल कर देती है।

8. (ग) (i), (ii) और (iv) तीनों

Physical Properties of Haloalkanes

1.    In general, haloalkanes are colourless, sweet smelling liquids. Bromides and iodides become colored when exposed to sunlight.
2.    Haloalkanes are polar in nature but practically they are very slightly soluble in water. It is due to the reason that they are not able to form hydrogen bonds with water. On the other hand, chloro, bromo and iodo derivatives are soluble in organic solvents such as alcohol, ether, benzene, etc. because intermolecular forces in these derivatives are similar to that in these solvents.
3.    With increasing size of the alkyl group, the densities of haloalkanes go on decreasing. Simple fluoro and chloro alkanes are lighter than water while bromides, iodides and polychloro derivatives are heavier than water. The densities increase in the order :
fluoride < chloride < bromide < iodide
4.    The melting and boiling points of chlorides, bromides and iodides are considerably higher than those of the parent hydrocarbon of comparable molecular mass. It happens because the intermolecular forces of attraction (dipole-dipole and van der Waal’s) between the molecules are stronger in halogen derivatives of alkanes due to the polarity of haloalkanes.
    ·    For the same alkyl group the boiling points of alkyl chlorides, bromides and iodides follow the order :
        RI > RBr > RCl < RF where R is an alkyl group.
It is because of the reason that with the increase in the size of the halogen, the magnitude of van der Waal’s forces increases and consequently, the boiling points increase as shown below :

  ·    In general, the boiling points of chloro, bromo and iodo compounds increases with increase in the number of halogen atoms.
       
 ·    For the same halogen atom, the boiling points of haloalkanes increase with increase in the size of alkyl groups.
   
  ·    The boiling points of isomeric alkyl halides decreases with branching. It happens due to the reason that branching of the chain makes the molecule more compact and therefore decrease the surface area. Due to decrease in surface area, the magnitude of van der Waal’s forces of attraction decreases and consequently, the boiling points of the branched chain compounds is less than those  of the straight chain compounds as shown below:
        n-Butylbromide > Iso-butylbromide > tert-Butyl bromide.