Plz hurry the star betelgeuse is 20 times more massive than the sun. what would be the likely impact on the motion of earth if the sun were replaced by betelgeuse? a)orbital radius would increase because the gravitational pull would decrease. b)orbital radius would decrease because the gravitational pull would increase. c)orbital velocity would decrease because the gravitational pull would increase. d)orbital velocity would increase because the gravitational pull would decrease.

B: Orbital radius would decrease because the gravitational pull would increase.

The gravitational force depends on the mass of the two bodies and the square of the distance between them. If the sun is replaced by Betelgeuse which is twenty times heavier, it would exert 20 times greater force on the Earth. Hence, it would pull the Earth closer. This would change its present orbit. The orbit would decrease.

Therefore, the right option is B: Orbital radius would decrease because the gravitational pull would increase.

when 25.0 ml of 0.700 mol/l naoh was mixed in a calorimeter with 25.0 ml of 0.700 mol/l hcl, both initially at 20.0 °c, the temperature increased to 22.1 °c. the heat capacity of the calorimeter is 279 j/°c.

the equation for the reaction is:

naoh + hcl → nacl + h₂o

moles of hcl = 0.0250 l hcl ×

0.700

mol hcl

1 l hcl = 0.0175 mol hcl

volume of solution = (25.0 + 25.0) ml = 50.0 ml

mass of solution = 50.0 ml soln ×

1.00

ml soln

= 50.0 g soln

δt=t2-t1

= (22.1 – 20.0) °c = 2.1 °c

the heats involved are

heat from neutralization + heat to warm solution + heat to warm calorimeter = 0

q1+q2+q3=0

nδh+mcδt+cδt=0

0.0175 mol ×

δh

+ 50.0 g × 4.184 j·g⁻¹°c⁻¹ × 2.1 °c + 279 j°c⁻¹ × 2.1 °c = 0

0.0175 mol ×

δh

+ 439.32 j + 585.9 j = 0

0.0175 mol ×

δh

= -1025.22 j

δh=1025.22j0.0175 mol= -58 600 j/mol = -58.6 kj/mol