(1 cal/g °C) x (4000 g) x (45 - 25)°C = 80000 cal = 80 kcal. So the answer is 80 kcal .
1. Frequency: 
The frequency of a light wave is given by:
where
is the speed of light
is the wavelength of the wave
In this problem, we have light with wavelength
Substituting into the equation, we find the frequency:
2. Period: 
The period of a wave is equal to the reciprocal of the frequency:
The frequency of this light wave is (found in the previous exercise), so the period is:
<em>The correct option is </em><em>A</em>. The information we know about the known exoplanets is estimates of orbits and masses.
<h3>What is exoplanets?</h3>
An exoplanet or extrasolar planet is a planet outside the Solar System.
In other words, exoplanet is any planet beyond our solar system.
<h3>Characteristics of exoplanets</h3>
exoplanets are known for the following characteristics;
- they are usually hot
- they can orbit their stars so tightly that a “year” lasts only a few days
- they can orbit two suns at once
Thus, the information we know about the known exoplanets is estimates of orbits and masses.
Learn more about exoplanets here: brainly.com/question/1514493
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The correct answer is:
c. convection.
The heating of magma and the continuous cycle of evolution of the magma creating a convection current is the reason for the evolution of Earths tectonic plates.
Explanation:
Tectonic plates are ready to move because the Earth's lithosphere has higher strength than the underlying asthenosphere. Lateral density changes in the mantle appear in convection. Plate movement is believed to be driven by a succession of the motion of the seafloor apart from the extended ridge (due to variations in topography and density of the crust.
