Answer:
D) 8
Explanation:
Due to the octet rule the most stable atoms will have 8 valence electrons.
 
        
             
        
        
        
but the points are only 25
 
        
                    
             
        
        
        
A radio telescope is simply a telescope that is designed to receive radio waves from space. In its simplest form it has three components:
1. One or more antennas to collect the incoming radio waves. Most antennas are parabolic dishes that reflect the radio waves to a receiver, in the same way as a curved mirror can focus visible light to a point.
2. A receiver and amplifier to boost the very weak radio signal to a measurable level. These days the amplifiers are extremely sensitive and are normally cooled to very low temperatures to minimise interference due to the noise generated by the movement of the atoms in the metal (called thermal noise).
3. A recorder to keep a record of the signal. Most radio telescopes nowadays record directly to some form of computer memory disk as astronomers use sophisticated software to process and analyse the data.
 
        
             
        
        
        
Answer: The wavelength and frequency of light are closely related. The higher the frequency, the shorter the wavelength. Because all light waves move through a vacuum at the same speed, the number of wave crests passing by a given point in one second depends on the wavelength.
Explanation:
 
        
             
        
        
        
Answer:
a) a =  i ^ +
 i ^ + j^, b) r = 2 v₃ T j ^, c)    v = -v₁ i ^ + (2 v₃ - v₂) j ^
 j^, b) r = 2 v₃ T j ^, c)    v = -v₁ i ^ + (2 v₃ - v₂) j ^
Explanation:
This is a two-dimensional kinematics problem
a) Let's find the acceleration of the body, for this let's use a Cartesian coordinate system
X axis
      
initial velocity v₀ₓ = v₁ for t = 0, velocity reaches vₓ = 0 for t = T, let's use
           vₓ = v₀ₓ + aₓ t
we substitute
           for t = T
            0 = v₁ + aₓ T
            aₓ = - v₁ / T
y axis  
        
the initial velocity is  = v₂ at t = 0 s, for time t = T s the velocity is v_{y} = v₃
 = v₂ at t = 0 s, for time t = T s the velocity is v_{y} = v₃
              v₃ = v₂ + a_{y} T
               a_{y} = 
therefore the acceleration vector is
              a =  i ^ +
 i ^ + j^
 j^
b) the position vector at t = 2T, we work on each axis
X axis
              x = v₀ₓ t + ½ aₓ t²
we substitute
              x = v₁ 2T + ½ (-v₁ / T) (2T)²
               x = 2v₁ T - 2 v₁ T
               x = 0
Y axis  
              y =  t + ½ a_{y} t²
 t + ½ a_{y} t²
              y = v₂ 2T + ½  4T²
 4T²
              y = 2 v₂ T + 2 (v₃ -v₂) T
             y = 2 v₃ T
the position vector is
             r = 2 v₃ T j ^
c) the velocity vector for t = 2T
X axis
             vₓ = v₀ₓ + aₓ t
we substitute
            vₓ = v₁ -  2T = v₁ - 2 v₁
 2T = v₁ - 2 v₁
            vₓ = -v₁
Y axis  
             = v_{oy} + a_{y} t
 = v_{oy} + a_{y} t
            v_{y} = v₂ +  2T
 2T
            v_{y} = v₂ + 2 v₃ - 2v₂
            v_{y} = 2 v₃ - v₂
the velocity vector is
            v = -v₁ i ^ + (2 v₃ - v₂) j ^