Gold is a soft, lustrous yellow metal. It is a 'd' block transition element in the periodic table. It belongs to period 6 and group IB.
This note has brief introduction about gold and its properties.
Gold is a soft, lustrous yellow metal. It is a 'd' block transition element in the periodic table. It belongs to period 6 and group IB.
This note has brief introduction about gold and its properties.
Things to Remember
Gold is a soft, lustrous yellow metal. It is a 'd' block transition element in the periodic table. It belongs to period 6 and group IB.
The physical properties of gold are; it possesses a lustrous yellow color, good conductor of heat and electricity, less reactive metal melting point is 10630C and boiling point is 26100C.
MCQs
No MCQs found.
Subjective Questions
Q1:
In the figure given below O, is the centre of enlargement and the number in the bracket near it is the scale factor of enlargement.Find the image.
Answer: <p>Soln:</p> <figure class="inline-left" style="width: 250px;"><img src="/uploads/1119.png" alt="." width="250" height="233"><figcaption><br></figcaption></figure><p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p>Consttruction procedure:</p> <p>To enlarge the triangle ABC with centre at O and scale factor 2 i. e. join O and A and produce it upto A' where OA' = 2OA. Also join O and B and O and C. Then produce OB and OC upto B' and C' where OB' = 2OB and OC' = 2OC. Then, if we join A', B' and C' then the triangle A'B'C' is the image of triangle ABC under the enlargemant with centre O and scale factor 2.</p>
Q2:
In the figure given below O, is the centre of enlargement and the number in the bracket near it is the scale factor of enlargement.Find the image.
Answer: <p>Soln:</p> <figure class="inline-left" style="width: 250px;"><img src="/uploads/qaz1.png" alt="." width="250" height="165"><figcaption><br></figcaption></figure><p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p>Construction procedure:</p> <p>Here, at first B, C and D are joined with O and then OB, OC and OD are produced upto B', C' and D' such that OB' = 3OB, OC' = 3OC and OD' = 3OD. Now, B', C' and D' are joined so that the triangle A'B'C'D' is the image of triangle BCD under the enlargement with centre at O and scale factor 3.</p>
Q3:
In the figure given below O, is the centre of enlargement and the number in the bracket near it is the scale factor of enlargement.Find the image.
Answer: <p>Soln:</p> <figure class="inline-left" style="width: 250px;"><img src="/uploads/qas1.png" alt="." width="250" height="146"><figcaption><br></figcaption></figure><p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p>Construction procedure:</p> <p>Here, at first CO, DO and Eo are produced upto C', D' and E' respectively such that OC' =\(\frac{1}{2}\)OC, OD' =\(\frac{1}{2}\)OD and OE' =\(\frac{1}{2}\)OE.</p> <p>Then C", D', E' and O are joined so that the parallelogram OC'D'E' is the image of parallelogram OECD under the enlargement with centre at O and scale factor \(-\frac{1}{2}\)</p>
Q4:
In the figure given below O, is the centre of enlargement and the number in the bracket near it is the scale factor of enlargement.Find the image.
Answer: <p>Soln:</p> <figure class="inline-left" style="width: 250px;"><img src="/uploads/1214.png" alt="." width="250" height="174"><figcaption><br></figcaption></figure><p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p>Construction procedure:</p> <p>Here, OF, OG, OH, OI and OJ are produced upto F', G', H', I' and J' as in the figure so that OF' = \(1\frac{1}{2}\)OF, OG' =\(1\frac{1}{2}\)OG, OH' =\(1\frac{1}{2}\)OH, OI' =\(1\frac{1}{2}\) and OJ' =\(1\frac{1}{2}\)OJ. Then join O, F, G, I and J so that the hexagon OF'G'H'I'J' is the image of hexagon OFGHIJ under the enlargement with the centre at O and scale factor \(1\frac{1}{2}\).</p>
Q5:
In the figure given below O, is the centre of enlargement and the number in the bracket near it is the scale factor of enlargement.Find the image.
Answer: <p>Soln:</p> <figure class="inline-left" style="width: 200px;"><img src="/uploads/258.png" alt="." width="200" height="186"><figcaption><br></figcaption></figure><p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p>Construction procedure:</p> <p>Here, as in the figure, QO, RO and PO are produced upto Q', R' and P' respectively so that OQ' = 2OQ, OR' = 2OR and OP = 2OP'. Now O, Q', R' and P' are joined so that the figure OP'Q'R' is the image of the figure OPQR under the enlargement with centre at O and scale factor -2.</p>
Q6:
In the figure given below O, is the centre of enlargement and the number in the bracket near it is the scale factor of enlargement.Find the image.
Answer: <p>Soln:</p> <figure class="inline-left" style="width: 200px;"><img src="/uploads/260.png" alt="." width="200" height="113"><figcaption><br></figcaption></figure><p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p>Construction procedure:</p> <p>Here, at first points B, C, D, E and F are joined with O. Then the points A', B', C', E', F' and G' are marked on the line OA, OB, OC, OD, OE, OF and OG respectively where OA' =\(\frac{3}{4}\)OA, OB' =\(\frac{3}{4}\)OB, OC' =\(\frac{3}{4}\)OC, OD' =\(\frac{3}{4}\)OD, OE' =\(\frac{3}{4}\)OE, OF' =\(\frac{3}{4}\)OF and OG' =\(\frac{3}{4}\)OG. Then the points A', B', C' D', E', F' and G' are joined so that the shaded figure A'B'C'E'F'G'F'G' is the image of the given figure under [0,\(\frac{3}{4}\)].</p>
Q7:
In the figure O is the centre of enlargement and the number in the bracket near it is scale factor of enlargement. Find the image.
Answer: <p>Soln:</p> <figure class="inline-left" style="width: 200px;"><img src="/uploads/263.png" alt="." width="200" height="113"><figcaption><br></figcaption></figure><p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p>Construction procedure:</p> <p>Here, as in figure, points A, B, C, D and E are joined with O. Then points A', B', C', D' and E' are marked on the line OA, OB, OC, OD and OE respectively where OA' =\(\frac{1}{2}\)OA, OB' =\(\frac{1}{2}\)OB, OC' =\(\frac{1}{2}\)OC, OD' =\(\frac{1}{2}\)OD and OE' =\(\frac{1}{2}\)OE. Now, the points A', B', C', D' and E' are joined so that the pentagon A'B'C'D'E' is the image of the pentagon ABCDE under the enlargement with centre at O and scale factor\(\frac{1}{2}\).</p>
Q8:
In the picture given below, the object and its image are given. Find the centre and scale factor of enlargement for each of the diagram given below.
Answer: <p>Soln:</p> <figure class="inline-left" style="width: 200px;"><img src="/uploads/267.png" alt="." width="200" height="127"><figcaption><br></figcaption></figure><p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p></p> <p>Procudure: Here, the lines AA', BB', CC' and DD' intersect at the point O. So that O is the centre of enlargement. Also from actual measurement,</p> <p>OA' = 4 cm</p> <p>OA = 1.5 cm</p> <p>\(\frac{OA'}{OA}\) =\(\frac{4}{1.5}\) =\(\frac{8}{3}\)</p> <p>∴ Scale factor =\(\frac{8}{3}\)</p> <p></p>
Q10:
Write down the coordinates and draw its image on a graph for each of the points given in question no.3 above with the following centres and scale factors of enlargement
IF \(\overrightarrow{PA}\)= \(\begin{pmatrix} a \\ b \\ \end{pmatrix}\), scale factor k and position vector of \(\overrightarrow{OP}\)=\(\begin{pmatrix} x \\ y \\ \end{pmatrix}\), then coordinates of A are A' (ka+x,kb+y)
Answer: <p>Soln: Here, let the centre be P (2,1) and scale factor k = 2 and A (2,0) be a point. so,</p> <p>∴ \(\overrightarrow{PA}\)=\(\begin{pmatrix} 2&-2 \\ o&-1 \\ \end{pmatrix}\)= \(\begin{pmatrix} 0 \\ -1 \\ \end{pmatrix}\)</p> <p>∴ A (2,0)→ A' (2×0+2,2×-1+1)=A.(2,-1)</p> <p>Also, Relation of P (2,1) and B (3,5)</p> <p>\(\overrightarrow{PB}\)= \(\begin{pmatrix} 3&-2 \\ 5&-1 \\ \end{pmatrix}\)=\(\begin{pmatrix} 1 \\ 4 \\ \end{pmatrix}\)</p> <p>∴ B (3,5)→ B' (2×1+2,2×4+1) = B'(4,9)</p> <p>Relation of P (2,1) and C (4,-7) is</p> <p>\(\overrightarrow{PC}\)=\(\begin{pmatrix} 4&-2 \\ -7&-1 \\ \end{pmatrix}\)=\(\begin{pmatrix} 2 \\ -8 \\ \end{pmatrix}\)</p> <p>∴ C= (4,-7)→C'(2×2+2,2×-8+1)=C'(6,-15)</p> <p>Relation of P (2,1) and D (-3,8) is</p> <p>\(\overrightarrow{PD}\)=\(\begin{pmatrix} -3&-2 \\ 8&-1 \\ \end{pmatrix}\)=\(\begin{pmatrix} -5 \\ 7 \\ \end{pmatrix}\)</p> <p>∴ D(-3,8)→D'(2×-5+2,2×7+1)=D'(-8,15)</p> <p>Relation of P (2,1) and F (-5,-7) is</p> <p>\(\overrightarrow{PF}\)= \(\begin{pmatrix} -5 &-2 \\ -7&-8 \\ \end{pmatrix}\)=\(\begin{pmatrix} -7 \\ -8 \\ \end{pmatrix}\)</p> <p>∴ F(-5,-7)→F'(2×-7+2,2×-8+1)=F'(-12,-15)</p> <p>Relation of P (2,1) and G (0,-11) is</p> <p>\(\overrightarrow{PG}\)= \(\begin{pmatrix} 0&-2 \\ -11&-1 \\ \end{pmatrix}\)=\(\begin{pmatrix}-2 \\ -1 \\ \end{pmatrix}\)</p> <p>∴ G(0,-11)→G'(2×(-2)+2,2×(-12)+1)=G'(-2,-23)</p> <p>The graph of the given points and their images under the enlargement with centre at P(2,1) and scale factor 2 is given below:</p>
Q11:
What are the values of p and q when the point A(1,p) is enlarged with centre as the origin and scale factor 2 to form an image A'(q,8)?
Answer: <p>Soln: Here given, image of point A(1,p) is A' (q,8) and centre of enlargement (o,o) and scale factor k=2</p> <p>We know that enlargement of P(x,y) under E[o,k] is P'(kx,ky)</p> <p>Sp, A (1,p)→A'(2.1)2p)=A'(2,2p)</p> <p>but, image of A is A'(q,8)</p> <p>So, (2,2P)=(q,8)</p> <p>or, 2=q amd 2p=8</p> <p>∴ p=4 and q=2. Ans.</p>
Q12:
If points A(-2,1), B(-2,4), C(4,4) and D(4,-1) are the vertices of rectangle ABCD which is enlarged with centre as the origin and scale factor 2, then write down the co-ordinates od the image so formed and present it on graph.
Answer: <p>Soln: Here, the enlargement of rectangle ABCD under centre at origin and scale factor2 that is [O,2] by using P(x,y)→P'(kx,ky) is as follow:</p> <p>A(-2,1)→A'(-2×2,1×2)=A'(-4,2)</p> <p>B(-2,4)→B'(-2×2,4×2)=B'(-4,8)</p> <p>C(4,4)→C'(4×2,4×2)-C'(8,8)</p> <p>D(4,1)→D'(4×2,1×2)=D'(8,2)</p> <p>Here, rectangle A'B'C'D' is the image of the rectangle under the enlargement [0,2], which is shown in the following graph paper.</p>
Q13:
In the figure given below O, is the centre of enlargement and the number in the bracket near it is the scale factor of enlargement.Find the image.
Answer: <p>Soln:</p> <p><strong>Construction procudure:</strong> Here as shown in the figure, R is joined with O, Here scale factor is 3, So the lines OP,OQ and OR are produced up to P', Q' and R' respectively so that OP'=3OP, OQ'=3OQ and OR' =3OR.Now, P',Q' and R', are joined so that the \(\triangle\) P',Q',R' of the images of \(\triangle\)PQR is prepared with centre at O and scale factor 3.</p> <p></p>
Q14:
The vertices of triangle ABC are A(2,4),B(-3,5) and C(-2,-3).Draw the image of the triangle ABC on the graph with the following enlargements.
Answer: <p>Soln:</p> <p>Enlargement of \(\triangle\) ABC under E[0,2]:</p> <p>A(2,4)→A'(2×2,4×2)=A'(4,8) ∴p(x,y)→P'(kx,ky)</p> <p>B(-3,5)→B'(-3×2,5×2)=B'(-6,10)</p> <p>C(-2,-3)→C'(-2×2,-3×2)=C'(-4,-6)</p> <p>\(\triangle\)A'B'C' is the image of \(\triangle\)ABC under E[0,2].Which is shown in the following graph.</p>
Q15:
The vertices of triangle ABC are A(2,4),B(-3,5) and C(-2,-3).Draw the image of the triangle ABC on the graph with the following enlargements.
Answer: <p>Soln:</p> <p>Enlargement of \(\triangle\) ABC under E[0,-2]:</p> <p>A(2,4)→A'(2×-2,4×-2)=A'(-4,-8) ∴p(x,y)→P'(kx,ky)</p> <p>B(-3,5)→B'(-3×-2,5×-2)=B'(6,-10)</p> <p>C(-2,-3)→C'(-2×-2,-3×-2)=C'(4,6)</p> <p>\(\triangle\)A'B'C' is the image of \(\triangle\)ABC under E[0,-2].Which is shown in the following graph.</p>
Videos
https://www.youtube.com/watch?v=Rw7DBXZs_k0
Maths Made Easy! Transformations #4: Enlargement
Transformations - Enlargements of Shapes
Gold
Symbol: Au Atomic No: 79 Atomic Weight: 197.2 Valency: 1 and 3 Electronic configuration: 1s2,2s2,2p6,3s2,3p6,3d10,4s2,4p6,4d10,4f14,5s2,5p6,5d10,6s1 Position in the periodic table: Gold is a soft, lustrous yellow metal. It is a 'd' block transition element in the periodic table. It belongs to period 6 and group IB.
Physical properties
Gold possesses a lustrous yellow color.
It has a melting point 1063°C and boiling point of 2610°C
It is a heavy metal with specific gravity 19.3.
It is a good conductor of heat and electricity.
It is less reactive metal.
Chemical properties of gold
Reaction with acid:
Gold is a noble metal and has no action with water, air, alkalis and acids. But it dissolves in aqua regia (3:1 ratio of conc. HCl and conc. HNO3) to give gold chloride, nitrosyl chloride and water.
