Your Question has its answer.
Answering to your question in a very shortcut way—
—————————————————————–
When you will show everybody will get a positive response so that they can help others, In this way, people come near to each other and shares their experience so in the future they can help altogether.
—————-
Help others and you will be happy.
If you want to gain happiness in your life; Trust me you need to help others so that it encourages other people to help.
I hope you will definitely understand as a citizen & being a human being.

Hi
friend,
If you really want to enjoy passive income, there are millions, billions even trillion of ways to make passive income but still, it all depends upon your active skill, learning process, expertise in the field, and consistent practice with lots of talents with skills.
Even you know everything then also you must try something special in which you are good at in your niche.
————-
freelancing.
cooking
YouTuber
bitcoin trading and exchange rates.
online teaching
babysitting
tuition master
coaching classes
Exercise Classes
consultancy work
Astrology work
medical clinic with Ayurvedic natural
and lots more…
>>>>>>
Just remember that nothing is the world is a lifetime passive income. You probably need to engage every time when you feel that you need to engage.
>>>>————–>>>>
For example:
if you are a freelancer and you provide traffic service to takido.io——-
—-What is your primary function as a seller to the buyer?
The primary function is to process the order of your buyer and send traffic to takido.io
if the buyer will say I don’t get results then come to takido.io make some engagements or tell to buyer, engage is been done by the buyer because once the visitors are been sent to takido.io then it is the buyer responsibility to look after and take care of visitors and make them attract and stick to the takido.io.————–what I wanted to say is engagement is required periodically and timely otherwise passive income will be lost.
—————
Good Luck!
—————

This is the easiest question to answer —-
The speed of light is about 299700 km/s and it depends on the properties & an object which it passes through.>>>I think it is the only medium through direct seeing or air.
——————
Refractive index – it depends
Reflection – it depends.
——————
The last word we always need to the calculator through which it passes.
>>>>>
My opinion
>>>>>

Dear Friend,
There is nothing such a thing that you need to wait for after eating and sleeping.
Trust me!
After eating food you can wait for at least 10-15 minutes that’s OK enough but don’t sleep, Just make yourself very comfortable and take rest for half an hour after a meal, not breakfast.
After Sleeping if you are going to eat something then first get your face and mouth washed and take 10 drops of water before eating for controlling your appetite and immune system.
You would feel good.
That’s it.