Answer:Simple Covalent substance
Explanation:Simple covalent substance describes a substance that has a low melting point and poor electrical conductivity because:
(1)melting point :For the covalent bond and intermolecular force that are present in a simple covalent substance,energy is needed to break the forces of attraction present. In the simple covalent substance, little energy is needed because the intermolecular forces present are broken because they are weaker compared to the covalent bond present.
Therefore, when simple covalent substance melts,only the intermolecular forces are broken leaving only the covalent bond in the substance.
(2) poor conductivity: for a substance to conduct electricity,it must have charged particles which are free to move to and fro.
But in the simple covalent substance,there are no charged particles that can be separated due to the covalent bond present in simple covalent substance.
Answer:
The mass of the massive object at the center of the Milky Way galaxy is 
Explanation:
Given that,
Diameter = 10 light year
Orbital speed = 180 km/s
Suppose determine the mass of the massive object at the center of the Milky Way galaxy.
Take the distance of one light year to be 9.461×10¹⁵ m. I was able to get this it is 4.26×10³⁷ kg.
We need to calculate the radius of the orbit
Using formula of radius
We need to calculate the mass of the massive object at the center of the Milky Way galaxy
Using formula of mass
Put the value into the formula
Hence, The mass of the massive object at the center of the Milky Way galaxy is
Explanation :
(1) Involuntary muscles are the muscles that are not controlled by our will.
(2) Tendons are the connective tissues that join the muscle to bones. Tendons are tissues that have fibers.
(3) Cardiac muscle is also involuntary muscles. For example heart muscle. It shows contraction and relaxation throughout life.
(4) Voluntary muscle is the muscles that are not controlled by our will.
(5) Biceps are the arm muscles.
Hence, this the required explanation as per options.
Mechanical advantage is the amount by which a machine multiplies input force. It is a measure of the force amplification using a tool or machine system.
