BIG BEGINNING

WHAT KILLED DINOSAURS A COMET OR ASTEROID ?

A speeding comet, rather than an asteroid, slammed into the Earth 65 million years ago and sparked the extinction of the dinosaurs, scientists claim. Many scientists believe the 180 km Chicxulub crater in Mexico was made by the impact that caused the extinction of dinosaurs and about 70 per cent of all species on Earth. The crater was probably blasted out by a faster, smaller object than previously thought, according to the new study presented at the 44th Lunar and Planetary Science Conference in The Woodlands, Texas. Evidence of the space rock's impact comes from a worldwide layer of sediments containing high levels of the element iridium, dubbed the Cretaceous-Paleogene (K-Pg) boundary, which could not have occurred on Earth naturally.

source-http://www.indiatimes.com/technology/science/what-killed-the-dinosaurs-comet-or-asteroid-68343.html

class x unit test solutions

Questions

1. Define nutrition. Which mode of nutrition is exhibited by fungi?
2. Differentiate b/w autotrophic nutrition and heterotrophic nutrition.
3. Name two features of photosynthesis and write their site.
4. What is the raw material for photosynthesis and from where plant get them?
5. Write the role of acid in stomach.
6. What process would you consider essential for maintaining life?

Solutions

1. The process to transfer the source of energy from outside the body of the organism which we call food,to the inside,i.e the process we call nutrition. The mode of nutrition exhibited by fungi is saprotrophic.
2. Autotrophic- the mode of nutrition in which organisms make their own food for their survival. For eg-plants etc...
   Heterotrophic- the mode of nutrition in which organisms depend upon other organisms for their food. for eg- human beings etc...
3. Two features of photosynthesis are …
   Light phase(light dependent)
   Dark phase(light independent)
4. Raw material for photosynthesis is water ,sunlight and carbon dioxide. plants get them from atmosphere.
5. Acids play a major role in our life. There are many types of acids. Some acids are very good for our health whereas some acids create some painful problems in our stomach. So, it depends upon the type of acid acting in our stomach.
6. Processes essential for maintaining life are nutrition, digestion and other life processes.
   If any doubt please ask..

CLASS 10- CHEMISTRY UNIT TEST SOLUTION

Ques 1: Complete the reaction: Pb(No3)2------->
Ans 1: 2Pb(No3)2-------->2Pbo+4No2+o2 
Ques 2: Write the balanced chemical equation for the following and identify the type of reaction in each case?
1.Zinc carbonate(s)---->Zinc oxide(s)+Carbon dioxide(g)
Ans: 2Znco3---->2Zno2+Co2 (Decomposition reaction)
2.Hydrogen(g)+Chlorine(g)------>Hydrogen chloride(g)
Ans: H2+cl2----->2Hcl (Combination reaction)
Ques 3: Differentiate between exothermic and endothermic reaction?
Ans 3: EXOTHERMIC REACTION: The chemical reaction in which product is formed by the evolution of heat .EX: Cao(s)+H2O(l)---->Ca(oH)2(aq)+Heat
ENDOTHERMIC REACTION: The chemical reaction in which the product is formed by the absorption of heat.EX:C(s)+H2O----->Co(g)+H2-Heat
Ques 4:A solution of substance"x" is used for white washing:
1. Name the substance x and write its formula?
Ans Calcium Oxide (Cao) is the substance x.
2. Write the reaction of the substance named in above with water?
Ans Cao+H2o----->Ca(oH)2(slaked lime)
Ques 5: Explai the following with example:
 Ans 5: DOUBLE DISPLACEMENT REACTION: The such reactions in which two compounds react by an exchange of ions to form new compound are called double dispacement reaction. Ex: Na2So4(aq)+Bacl2(aq)------->2Nacl(aq)+BaSo4(s)
NEUTRALIZATION REACTION: Such reactions in which acid is reacted with base to form salt and water. Ex: Hcl+NaoH+Nacl+H2o
DISPLACEMENT REACTION: Those reactions in which more active element displaces or remove a less active element from its compound. Ex: Zn(s)+CuSo4----->ZnSo4+Cu

Did You Know?

Depending on how old you are, it's pretty likely that you have eyelash mites. These tiny creatures live on old skin cells and the natural oil (sebum) produced by human hair follicles. They are usually harmless, though they can cause an allergic reaction in a minority of people. Eyelash mites typically grow to a third of a millimetre and are near-transparent, so you are unlikely to see them with the naked eye. Put an eyelash hair or eyebrow hair under the microscope, though, and you may find them, as they spend most of their time right at the base of the hair where it meets the skin. Around half the population have them, a proportion that rises as we get older.

source:
http://www.indiatimes.com/science/amazing-science-facts-

THINK FASTER,FOCUS BETTER,REMEMBER MORE

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