Answer:
240 seconds
Explanation:
Data Given:
Distance Radio travel to earth = 7.19 ×10⁷ km
Speed of this radio signal = 3.00 ×10⁸ m/s
Solution:
First convert Km to m
1 km = 1000 m
7.19 ×10⁷ km = 7.19 ×10⁷ x 1000 = 7.19 × 10¹⁰m
Formula used to calculate time
Speed (S) = distance (d) / time (t)
rearrange above equation for time
time (t) = distance (d) / Speed (S) . . . . . . . . .(1)
Put values in equation 1
time (t) = 7.19 × 10¹⁰/ 3.00 ×10⁸ m/s
time (t) = 240 s
So 240 seconds it take for the signal to reach the earth
Scientists use special tools to do their work. They gather data, or information, as they seek to learn about the world. In order to solve problems they must record data that is accurate and organized. This is an important part of the scientific method.
<em>Answer:</em>
<em>Chemical properties:</em>
Those properties which change the chemical nature of matter.
<em>Example:</em>
- Heat of combustion
- Enthalpy of formation
<em>Physical properties:</em>
Those properties which do not change the chemical nature of matter.
<em>Example</em>
<em>Differences between chemical and physical properties:</em>
Chemical properties Physical properties
1. Observed after the change bringing 1. Observed with out being
the change change
2. These changes the molecules 2. only change physical state
3. Chemical identity changes 3.Chemical identity not changes
4. Structure of material changes 4.Structure of material not change
5. Chemical reaction is needed 5. No need of Chemical reaction
6. depend on composition 6. Does not depend on composition
The given mass of cobalt chloride hydrate = 2.055 g
A sample of cobalt chloride hydrate was heated to drive off waters of hydration and the anhydrate was weighed.
The mass of anhydrous cobalt chloride = 1.121 g anhydrate.
The mass of water lost during heating = 2.055 g - 1.121 g = 0.934 g
Converting mass of water of hydration present in the hydrate to moles using molar mass:
Mass of water = 0.934 g
Molar mass of water = 18.0 g/mol
Moles of water = 
