Sets

Question 1.

State whether or not the following elements form a set; if not, give reason:

(i) All easy problems in your text book.

(ii) All three sided figures.

(iii) The first five counting numbers.

(iv) All the tall boys of your class.

(v) The last three days of the week.

(vi) All triangles that are difficult to draw.

(vii) The first three letters of the English alphabet.

(viii) All tasty fruits.

(ix) All clever boys of class 6.

(x) All good schools in Delhi.

(xi) All the girls in your class, whose heights are less than your height.

(xii) All the boys in your class, whose heights are more than your height.

(xiii) All the problems in your Mathematics book, which are difficult for Amit.

Solution:

Question 1.If set A = {2, 3, 4, 5, 6}, state which of the following statements arc true and which are false :

(i) 2 ∈ A

(ii) 5, 6 ∈ A

(iii) 3, 4, 7 ∈ A

(iv) 2, 8 ∈ A

Solution:

Solution

Question 2.

If set B = {4, 6, 8, 10, 12, 14}. State, which of the following statements is correct and which is wrong :

(i) 5 ∈ B

(ii) 12 ∈ B

(iii) 14 ∈ B

(iv) 9 ∈ B

(v) B is a set of even numbers between 2 and 16.

(vi) 4,6 and 10 are die members of the set B. Also, write the wrong statements correctly.

Solution:

Question 3.

State, whether true or false :

(i) Sets {4, 9, 6,2} and {6, 2, 4, 9} are not the same.

(ii) Sets {0, 1, 3, 9, 4} and {4, 0, 1, 3, 9} are the same.

(iii) Sets {5, 4} and {5, 4, 4, 5} are not the same.

(iv) Sets {8, 3} and {3, 3, 8} are the same.

(v) Collection of vowels used in the word ‘ALLAHABAD’ forms a set.

(vi) If P is the set of letters in the word ‘ROOP’; then P = (p, o, r)

(vii) If M is the set of letters used in the word ‘MUMBAI’, then: M = {m, u, b, a, i}

Solution:

Question 4.

Write the set containing :

(i) the first five counting numbers.

(ii) the three types of angles.

(iii) the three types of triangles.

(iv) the members of your family.

(v) the first six consonants of the English Alphabet.

(vi) the first four vowels of the English Alphabet.

(vii) the names of any three Prime-Ministers of India.

Solution:

Question 5.

(a) Write the members (elements) of each set given below :

(i) {3, 8, 5, 15, 12, 7}

(ii) {c, m, n, o, s}

(b) Write the sets whose elements are :

(i) 2, 4, 8, 16, 64 and 128

(ii) 3, 5, 15, 45, 75 and 90

Solution:

Question 6.

(i) Write the set of letters used in the word ‘BHOPAL’.

(ii) Write the set of vowels used im the word ‘BENGAL’.

(iii) Write the set of consonants used in the word ‘HONG KONG’.

Solution:

Metals reactions with Air

Metals react with air, specifically with the oxygen in the air, to form metal oxides. This is a type of oxidation reaction. Here are a few examples:

1. Sodium (Na) reacts vigorously with air to form sodium oxide (Na2O).

2. 4Na + O2 → 2Na2O

3. Iron (Fe) reacts with oxygen in the air to form iron(III) oxide, commonly known as rust.

4. 4Fe + 3O2 → 2Fe2O3

5. Aluminum (Al) reacts with oxygen to form aluminum oxide (Al2O3).

6. 4Al + 3O2 → 2Al2O3

The reactivity of metals with air varies. Some metals, like gold and platinum, do not react with air at all.

Metals and non metals Questions and answers

Metals:

1. Metals are usually solid at room temperature (except mercury).

2. They are good conductors of heat and electricity.

3. Metals are malleable (can be hammered into thin sheets) and ductile (can be drawn into wires).

4. They have a shiny appearance, or luster.

5. Metals tend to lose electrons and form positive ions (cations).

Non-metals:

1. Non-metals can be solid, liquid, or gas at room temperature.

2. They are poor conductors of heat and electricity.

3. Non-metals are not malleable or ductile; they are brittle.

4. They do not have a shiny appearance.

5. Non-metals tend to gain electrons and form negative ions (anions).

Metalloids: There are also elements called metalloids that have properties in between metals and non-metals. Examples include silicon and germanium..etalloids: There are also elements called metalloids that have properties in between metals and non-metals. Examples include silicon and germanium..