5. Liquids generally have lower density as compared to solids. But you must have
observed that ice floats on water. Find out why?
ASSIGNMENT - 2
1.. What is meant by the term chemical formula?
2.. Write the chemical formulae of the following.
(i) Magnesium chloride
(ii) Calcium oxide
(iii) Copper nitrate
(iv) Aluminium chloride
(v) Calcium carbonate
3. What is basic different between atoms and molecules?
4.Calculate the molecular mass of:
H2
02
Cl2
Co2
CH4
C2H6
C2H4
NH3
CH3OH
5. What are polyatomic ions? Give examples.
Matrix
Global
School
ASSIGNMENT - 3
1. What is basic different between atoms and molecules?
2. Where are proteins synthesized inside the cell?
3. Who discovered cells and how?
4. Why is the cell called the structural and functional unit of life?
5. How do substances like CO2 and water move in and out of the cell? Discuss.
ASSIGNMENT -4
1. Why are lysomes known as succide bags?
2.Where proteins synthesized inside the cell?
Answers
Explanation:
5 ans:Liquids generally have lower density as compared to solids but ice floats on water. ... These spaces are larger as compared to spaces in water molecules. Thus the volume of ice is greater than water. Hence the density of ice is less than of water.
assignment 2 :
1l A chemical formula tells us the number of atoms of each element in a compound. It contains the symbols of the atoms of the elements present in the compound as well as how many there are for each element in the form of subscripts.
2. MgCl2
b) CaO
c) Cu (No3)2
d) AlCl3
e) CaCo3
3 1) Molecule is a group of two or more atoms combined together so it is bigger. 2) Atom consists of nucleus (containing protons and neutrons) and electrons. 2) Molecule consists of combination of two or more like or different atoms chemically bound together e.g. H2, HCl, NaCl etc. ... 4) Atom cannot be further divided.
4. molecular mass:
i) Molecular mass of H2= 2 x Atomic mass of H= 2 x 1
= 2 u
ii) Molecular mass of O2= 2 x Atomic mass of O
= 2 x 16
= 32 u
iii) Molecular mass of Cl2= 2 x Atomic mass of Cl
= 2 x 35.5
= 71 u
iv) Molecular mass of CO2= Atomic mass of C + 2 x Atomic mass of O
= 12 + 2 x 16
= 44 u
v) Molecular mass of CH4= Atomic mass of C + 4 x Atomic mass of H
= 12 + 4 x 1
= 16 u
vi) Molecular mass of C2H6= 2 x Atomic mass of C + 6 x Atomic mass of H
= 2 x 12 + 6 x 1
= 30 u
vii) Molecular mass of C2H4= 2 x Atomic mass of C + 4 x Atomic mass of H
= 2 x 12 + 4 x 1
= 28 u
viii) Molecular mass of NH3= Atomic mass of N + 3 x Atomic mass of H
= 14 + 3 x 1
= 17 u
ix) Molecular mass of CH3OH= Atomic mass of N + 3 x Atomic mass of H
= 12+ 4 x 1+16
= 32 u4
5 ans:Polyatomic ions are ions which consist of more than one atom. For example, nitrate ion, NO3-, contains one nitrogen atom and three oxygen atoms. The atoms in a polyatomic ion are usually covalently bonded to one another, and therefore stay together as a single, charged unit.
assignment 3:
1. The tiny particle of a chemical element, which may or may not exist independently is called an atom. Molecules refer to the set of the atoms held together by the bond, indicating the smallest unit of a compound. ... Two or more identical or different atoms bonded chemically.
2. Ribosomes are the sites in a cell in which protein synthesis takes place. Cells have many ribosomes, and the exact number depends on how active a particular cell is in synthesizing proteins.
3. The cell theory, or cell doctrine, states that all organisms are composed of similar units of organization, called cells. The concept was formally articulated in 1839 by Schleiden & Schwann and has remained as the foundation of modern biology. The idea predates other great paradigms of biology including Darwin’s theory of evolution (1859), Mendel’s laws of inheritance (1865), and the establishment of comparative biochemistry (1940).
First Cells Seen in Cork
While the invention of the telescope made the Cosmos accessible to human observation, the microsope opened up smaller worlds, showing what living forms were composed of. The cell was first discovered and named by Robert Hooke in 1665. He remarked that it looked strangely similar to cellula or small rooms which monks inhabited, thus deriving the name. However what Hooke actually saw was the dead cell walls of plant cells (cork) as it appeared under the microscope. Hooke’s description of these cells was published in Micrographia. The cell walls observed by Hooke gave no indication of the nucleus and other organelles found in most living cells. The first man to witness a live cell under a microscope was Anton van Leeuwenhoek, who in 1674 described the algae Spirogyra. Van Leeuwenhoek probably also saw bacteria.
4.Cells are called the structural and functional unit of life because all the living organisms are made up of cells and also all the functions taking place inside the body of organisms are performed by cells.
5. The substances like CO2 and water move in and out of a cell by diffusion from the region of high concentration to low concentration. When the concentration of CO2 and water is higher in external environment than that inside the cell, CO2 and water moves inside the cell.
assignment 4 :
1. Lysosomes are known as suicide bags of the cell because they contain lytic enzymes capable of digesting cells and unwanted materials.
When lysosomes burst, the lytic enzymes within the organelle spill all over the cell, rupturing the cell membrane or cell wall and inducing the death of the cell.
2.In eukaryotic cells, proteins are synthesised in the rough endoplasmic reticulum or RER as ribosomes are present on the membrane of RER. Proteins are synthesised by the ribosomes and enter the cisternae of endoplasmic reticulum through channels present in the membrane.
Answer:
two or atoms combine together to form molecule