Differentiate between metal and non-metal on the basis of their chemical properties.
Metal | Non-Metal |
---|---|
Metals are electropositive. | Non-metals are electronegative. |
They react with oxygen to form basic oxides. 4Na + O2 → 2Na2O These have ionic bonds. |
They react with oxygen to form acidic or neutral oxides. C + O2 → CO2 These have covalent bonds. |
They react with water to form oxides and hydroxides. Some metals react with cold water, some with hot water, and some with steam.
2Na + 2H2O → 2NaOH + H2 ↑ |
They do not react with water. |
They react with dilute acids to form a salt and evolve hydrogen gas. However, Cu, Ag, Au, Pt, Hg do not react. 2Na + 2HCl → 2NaCl + H2 ↑ |
They do not react with dilute acids. These are not capable of replacing hydrogen. |
They react with the salt solution of metals. Depending on their reactivity, displacement reaction can occur. CuSO4 + Zn → ZnSO4 + Cu |
These react with the salt solution of non-metals. |
They act as reducing agents (as they can easily lose electrons). Na → Na+ + e- |
These act as oxidising agents (as they can gain electrons). Cl2 + 2e- → 2Cl- |
When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
Outline a project which aims to find the dominant coat colour in dogs.
Draw the structure for the following compounds.
(i) Ethanoic acid (ii) Bromopentane*
(iii) Butanone (iv) Hexanal.
*Are structural isomers possible for bromopentane?
A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?
How is the sex of the child determined in human beings?
(a) What property do all elements in the same column of the Periodic Table as boron have in common?
(b) What property do all elements in the same column of the Periodic Table as fluorine have in common?
Calculate the number of electrons constituting one coulomb of charge.
What is an homologous series? Explain with an example.
Why is variation beneficial to the species but not necessarily for the individual?
A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?
What will be the formula and electron dot structure of cyclopentane?
The brain is responsible for
(a) thinking.
(b) regulating the heart beat.
(c) balancing the body.
(d) all of the above.
What are alloys?
Outline a project which aims to find the dominant coat colour in dogs.
Name
(a) three elements that have a single electron in their outermost shells.
(b) two elements that have two electrons in their outermost shells.
(c) three elements with filled outermost shells.
Define the unit of current.
Besides gallium, which other elements have since been discovered that were left by Mendeléev in his Periodic Table? (any two)
Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other? Name this gas.
The kidneys in human beings are a part of the system for
(a) nutrition. (c) excretion.
(b) respiration. (d) transportation.
The essential difference between an AC generator and a DC generator is that
(a) AC generator has an electromagnet while a DC generator has permanent magnet.
(b) DC generator will generate a higher voltage.
(c) AC generator will generate a higher voltage.
(d) AC generator has slip rings while the DC generator has a commutator.