The Lewis structure/diagram for CH2O (aka Formaldehyde) can be written in either of the following ways shown in the picture.
The dots represent electrons in the valence shell of the atom (the outermost shell). The green dots are electrons that belong to the Oxygen atom, the blue belong to the Carbon atom, and the pink belong to the Hydrogen atoms.
Covalent bonds are bonds between atoms where atoms share electrons with each other. Atoms bond because they obey the octet rule ( the rule states that most atoms of main-group elements tend to want 8 electrons in their valence shells).
Oxygen has 6 valence electrons, Carbon has 4, and Hydrogen has 1. H does not follow the octet rule, but C and O do, so the atoms are arranged in this way so that the O and C atoms have a full octet of electrons in their valence.
A. making an observation.
Explanation:
When scientists use one of their five sense to gather information, they are simply making an observation.
Most physical properties of matter are studied using sense of taste, of feel, sight, hearing and smell.
- Observation is the act of making a measurement or studying.
- It helps to investigate particular phenomenon in nature.
- Most observations made with our senses are usually qualitative in nature.
- They cannot be assigned values like quantitative ones.
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Observations brainly.com/question/5096428
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solution:
You need to find the frequency, and they have already given you the wavelength. And since you already know the speed of light, you can use formula (2) to answer this problem. Remember to convert the nano meters to meters because the speed of light is in meters. 

Water boils when its vapor pressure equals the prevailing atmospheric pressure over the water. In order for water to boil at 50 ºC, the pressure over the water would need to be reduced to a point greater equal to the vapor pressure of the water (92.5 torr).