Answer: 
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The balanced equation will be:

Characteristic properties can be used to describe and identify the substances, while non-characteristic properties, although can be used to describe the substances, cannot be used to identify them.
Temperature, mass, color, shape and volume are examples of non-characteristic properties.
Density, boiling point, melting point, chemical reactivity are examples of characteristic properties.
List of the properties observed by the scientist:
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Property Type of property
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Volume: 5 ml non-characteristic
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Color: blue non-characteristic
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State: liquid characteristic
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density: 1.2 g/cm characteristic
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Reaction: reacts with CO2 characteristic
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Answer:
V = 2600ms⁻¹
Explanation:
Given parameters:
Wavelength(λ) = 13meters
Period (T) = 0.005s
Period(T) is the time it takes for a full cycle of vibration to pass through. It's unit is in seconds (s)
The Velocity of waves is expressed as:
V = fλ
Where f = frequency(s⁻¹)
Frequency of a wave is the number of waves that passes through a point per unit time
f = 1/T
Where T is the period
We can therefore express Velocity of waves as a function of period
V = λ/T
Inputing the parameters, we have:
V = 13m / 0.005s
V = 2600ms⁻¹
What did Dalton's atomic theory contribute to science?
Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass.