Without being provided a list of items, I would have to generally say that everything around you is matter. There are a few exceptions to this list, but a general rule of thumb is anything you can touch, taste, smell or hold would be considered matter. Sound, light, time (Dr. Who may disagree) and heat would be considered non-matter items.
Answer:
Magnitude of its angular momentum = 0.0017 kgm²/s
Explanation:
Angular momentum, L = Iω
I is mass moment of inertia and ω is angular velocity.
Phonograph is in disc shape,

Radius = 0.5 x 48 = 24 cm = 0.24 m
Angular velocity, ω = 3.2 rad/s
Mass, M = 18 g = 0.018 kg
Substituting

Magnitude of its angular momentum = 0.0017 kgm²/s
Answer:
The magnitude of electrostatic force on each charge is quarter of the magnitude of initial electrostatic force. ( ¹/₄ F)
Explanation:
The electrostatic force between two charges is given by Coulomb's law;

where;
Q₁ and Q₂ are the magnitude of the charges
r is the distance between the charges
k is Coulomb's constant
Since the charges are identical;
Q₁ = Q
Q₂ = Q
the electrostatic force experienced by each charge is given by;

When each of the spheres has lost half of its initial charge;
Q₁ = Q/2
Q₂ = Q/2

Therefore, the magnitude of electrostatic force on each charge is quarter of the magnitude of initial electrostatic force.