prime numbers

The nucleus is the "brain" of the cell. Its job is to control the cell's structure, function, growth and division. It is usually located in the center of the cell, where it is enclosed in a membrane called the nuclear envelope – which like the cell membrane is also a semi-permeable barrier. The nuclear envelope is a double membrane as shown in the diagram.
The nucleus communicates with the rest of the cell through the nuclear pores. The nucleus is like a vault. It holds the cell's DNA -- which contains the genetic instructions for the cell's activities. In the diagram there is a structure within the nucleus called the nucleolus. This structure is the place where ribosomes are made. Ribosomes are very important structures upon which proteins are formed within the cell. In the diagram above, you can see the ribosomes that have already been sent out of the nucleus and are on the endoplasmic reticulum, one of the places within the cell where proteins are made.
One way the nucleus directs activities within the cell is by sending instructions through its envelope to the various organelles in the cell's cytoplasm. There are two main types of organelles -- organelles that produce protein and organelles that transfer chemical energy present in food molecules such as glucose into molecules called ATP (short for adenosine triphosphate). The chemical energy present in ATP can then be used by the cell for such activities as movement and building large molecules.

PRACTICE QUESTIONS ON CHEMICAL PROPERTIES METALS AND NON METALS

Q1    Show that MgO is a basic oxide. Give suitable equations also.

Q 2   shows that CO₂  is an acidic oxide. Give suitable equations also.

Q3    Name the metal that reacts a) vigorously with air at room temperature.

                                                        b) On prolonged heating.

Q 4   A metal X on heating gives a white powdery substance.

                a) Identify the metal ‘X’

                 b)  Write the chemical formulae and name of the white substance formed.

                c) Write the chemical equation for the same.

                d) What will happen if this powder is dissolved in water? Name the compound formed.  Also write the chemical   equation for the same.

                 e) What will happen when red litmus is dipped into the above solution?

                 f) What will happen when blue litmus is dipped into it?

                 g)  What is the nature of the solution formed?

Q5  Name the metal that reacts vigorously with cold water.

Q6   Name the gas liberated when metals reacts with water.

Q7  Name the gas liberated when metals reacts with acids.

Q8  How will you test for the presence of hydrogen gas?

Q9  Name two metals that do not react with water.

Q10 Name one non metal that is kept under water. Why?

Q11 Why sodium is kept under kerosene?

Q12  What happens when

                         a) An active metal is placed in water.

                         b) A magnesium ribbon is kept in a test tube containing hot boiling water.

                         c) Gold is place in test tube containing NaOH.

                         d) When Dilute HCl is kept for three days in a copper container.

                         e)  Name two metals that react with conc. H2SO4.

Q13  Why food stuff should not be placed in a metal container.