Perimeter = 4 × side, so side = 40/4 = 10 cm.

pH = 3 means [H+] = 10^-3 M = 0.001 M.

For a weak acid, pH ≈ pKa for a 0.1 M solution, so pH ≈ 4.76.

Circumference = 2πr = 2 × (22/7) × 7 = 44 cm.

Original area = π(10)² = 314 cm²; New area = π(8)² = 201.06 cm². Change = 314 - 201.06 = 112.94 cm².

Area = πr²; if r is doubled, area = π(2r)² = 4πr², so it quadruples.

Circumference = 2πr. If radius is halved, new circumference = 2π(r/2) = πr, which is halved.

Circumference = 2πr. If radius is halved, new circumference = 2π(r/2) = πr, which is halved.

Area increases by a factor of (3r)²/r² = 9.

Weight is inversely proportional to the square of the radius. If radius increases by 50%, weight decreases by 25%.

If the radius increases while mass remains constant, g decreases because g = G * M / r^2.

Gravitational acceleration g = GM/R². If R increases, g decreases.

Using the Arrhenius equation, if the rate doubles for a 10°C increase, Ea is approximately 40 kJ/mol.

The order of the reaction is third because the rate is proportional to the concentration raised to the power of 3.

The reaction is second-order because the rate depends on the square of the concentration of A.

According to Ohm's law, I = V/R. If R is doubled, I will be halved.

Max revenue occurs at x = -b/(2a) = 100/(2*2) = 25.

Using the sum and product of roots: 1 + (-3) = -2 and 1 * (-3) = -3, thus k = 3.

The discriminant must be greater than zero: 2² - 4*1*k > 0, which simplifies to k < 1.

Using the product of roots: k = (-2)(-3) = 6.

Using the sum and product of roots: k = 1*4 = 4, and sum = 1 + 4 = 5, thus k = 7.

Using the sum of roots (-3 + -4 = -7) and product of roots (-3*-4 = 12), we find p = 12.

Using the sum of the roots: p = -(3 + 4) = -7.

The speed of light in a medium is given by v = c/n. Thus, v = (3 x 10^8 m/s) / 1.33 ≈ 2.26 x 10^8 m/s.

To convert m/s to km/s, divide by 1000. Therefore, 3 x 10^8 m/s = 300000 km/s.

The speed of light in a medium is given by v = c/n. Therefore, v = (3 x 10^8 m/s) / 1.5 = 2 x 10^8 m/s.

To convert m/s to km/s, divide by 1000. Therefore, 3 x 10^8 m/s = 3 x 10^5 km/s.

Impedance (Z) = Voltage (V) / Current (I) = 120V / 5A = 24Ω.

Using Ohm's law, I = V/Xc = 100 V / 50 Ω = 2 A.

Using Ohm's law, I = V/Xc = 100 V / 50 ohms = 2 A.