The most common method astronomers use to determine the composition of stars, planets, and other objects is spectroscopy. This process utilizes instruments with a grating that spreads out the light from an object by wavelength. This spread-out light is called a spectrum. Every element has a unique fingerprint that allows researchers to determine what it is made of.
The fingerprint often appears as the absorption of light. Every atom has electrons, and these electrons like to stay in their lowest-energy levels. But when photons carrying energy hit an electron, they can push it to higher energy levels. This is absorption, and each element’s electrons absorb light at specific wavelengths related to the difference between energy levels in that atom. But the electrons want to return to their original levels, so they don’t hold onto the energy for long. When they emit the energy, they release photons with exactly the same wavelengths of light that were absorbed in the first place. An electron can release this light in any direction, so most of the light is emitted in directions away from our line of sight. Therefore, a dark line appears in the spectrum at that particular wavelength.
Because the wavelengths at which absorption lines occur are unique for each element, astronomers can measure the position of the lines to determine which elements are present in a target. The amount of light that is absorbed can also provide information about how much of each element is present.
Answer:
The reaction is an exothermic reaction .
The value of q is -880 kilo Joules.
Explanation:
Exothermic reactions are defined as the reactions in which energy of reactants is more than the energy of the products. In these reactions, energy is released by the system. The total enthalpy of the reaction 
comes out to be negative.
According to reaction, 2 moles of ammonia when reacts with 3 moles of nitrous oxide to give 4 moles of nitrogen gas and 3 moles of water vapor, along with release of 880 kJ of heat energy.
Since, heat is evolved during the course of reaction which means that reaction is an example of Exothermic reaction.
The reaction is an exothermic reaction .
The value of q is -880 kilo Joules.
Air is mainly composed of N2 (78%), O2 (21%) and other trace gases. Now, the total pressure of air is the sum of the partial pressures of the constituent gases. The partial pressure of each gas, for example say O2, can be expressed as:
p(O2) = mole fraction of O2 * P(total, air) ----(1)
Thus, the partial pressure is directly proportional to the total pressure. If we consider a sealed container then, as the temperature of air increases so will its pressure. Based on equation (1) an increase in the pressure of air should also increase the partial pressure of oxygen.
I would go with C because that seems like the best answer choice
The dark smooth areas on the surface of the moon is called Maria.
Maria is made up of solidified lava which is a result of volcanic activity on the moon.
When Galileo observed these smooth dark spots on the moon he called them 'mare' which is latin for 'sea'. And the plural form of mare is 'maria'. Unlike Galileo predictions, recent investigations confirm that maria are not oceans but solidified lava.
