Hydrogen gas (H2) is a promising alternative to fossil fuels. How many molecules are present in 1.0 kg of hydrogen gas

3.01×10²⁶ molecules

Explanation:

From the question given above, the following data were obtained:

Mass of H₂ = 1 Kg

Number of molecules =?

From Avogadro's hypothesis,

1 mole of H₂ = 6.02×10²³ molecules

But 1 mole of H₂ = 2 × 1 = 2 g

Now, we shall determine the number of molecules present in 1 Kg (i.e 1000 g) of H₂ as follow:

From Avogadro's hypothesis,

2 g of H₂ = 6.02×10²³ molecules

Therefore,

1000 g of H₂ = 1000 × 6.02×10²³ / 2

1000 g of H₂ = 3.01×10²⁶ molecules

Thus, the number of molecules present in 1 Kg (i.e 1000 g) of H₂ is 3.01×10²⁶ molecules

the answer is definitely c.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.