Kepler's first law explains that the sun is the focus of our solar system, and that the orbit of a planet around the sun is an ellipse the speeds of the sun, moon, and stars are perfectly uniform and unchanging the orbits of the sun, moon, and stars are perfect circles the moon is not in orbit around the sun

The correct answer is A) the orbit of a planet around the sun is an ellipse the speeds of the sun.

Kepler's first law explains that the sun is the focus of our solar system and that the orbit of a planet around the sun is an ellipse the speeds of the sun.

The three laws of Kepler are the following. The Law of Orbits: all planets move in an elliptical orbit, with the sun at one focus.

The Law of Areas: a line that connects a planet to the sun sweeps out equal areas in equal times.

The Law of Periods: the square of the period of a planet is proportional to the cube of the semimajor axis of its orbits.

gravity causes stares to cluster i think so

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