Question

On mixing iron sulphate with aluminium the green colour of the ferrous sulphate solution will become
Blue
colourless
No change in colour
None of the above
Other:​

Answer 1

Answer:In activity series, the elements on the top can displace element at the bottom but not vice versa. From the given question, Aluminium can displace iron and copper sulphate solutions. Hence, colour change will be observed in Test-Tube A and Test-tube B. Iron metal cannot displace aluminium but can displace copper sulphate solution. Hence Test-tube D’s colour will change too.

Thus, colour change observed in A, B and D.

Since aluminium displaces both the elements, it is the most reactive elements among all. It is above both the elements in the activity series

Answer 2

Answer:

The length, area and the perimeter of the rectangle are 21cm, 420 cm² and 82 cm respectively.

Step-by-step explanation:

Let the rectangle be ABCD.

According to the question :

➟ Diagonal : BD = 29cm

➟ Breadth : CD = 20cm

All the angles in a rectangle are 90°.

So, ∆BDC is a right angled triangle with ∠BCD = 90°. Using pythagoras theorem :

➟ (P)² + (B)² = (H)²

➟ (BC)² + (20)² = (29)²

➟ BC² + 400 = 841

➟ BC² = 841 – 400

➟ BC² = 441

➟ BC = √441

➟ BC = 21cm

∴ The length of the rectangle BC is 21 cm.

Now, let's find the area of the rectangle :

➟ Area of rectangle = Length × breadth

➟ A = 21cm × 20cm

➟ Area = 420cm²

∴ The area of the rectangle is 420 cm².

Finally, finding the perimeter of the rectangle :

➟ Perimeter = 2 (l + b)

➟ P = 2 (21cm + 20cm)

➟ P = 2 (41cm)

➟ Perimeter = 82cm

∴ The perimeter of the rectangle is 82 cm.

Explanation:

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