Answer : The mass of oxygen formed must be 3.8 grams.
Explanation :
Law of conservation of mass : It states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
This also means that total mass on the reactant side must be equal to the total mass on the product side.
The balanced chemical reaction will be,

According to the law of conservation of mass,
Total mass of reactant side = Total mass of product side
Total mass of
= Total mass of 
As we are given :
The mass of
= 25.3 grams
The mass of
= 23.4 grams
So,



Therefore, the mass of oxygen formed must be 3.8 grams.
.009375 kg or 9.375 grams will remain
A. both permanent magnets and electromagnets.
Explanation:
A permanent magnet can affect and attract any other permanent magnet and even electromagnet.
They also affect any magnetic materials especially metals that can be magnetized.
In the vicinity of such substances, an attractive or repulsive force sets in and they both interact in the presence of the force field in place.
Permanent magnets cannot magnetize non-magnets.
An electromagnet is a magnet produced by the passage of electric current through a wire wound round a metallic core.
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Electromagnet brainly.com/question/2191993
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Answer:
gravity that's what I rellat think it is