Answer:

Explanation:
Given that:
Half life = 30 min
Where, k is rate constant
So,
The rate constant, k = 0.0231 min⁻¹
Using integrated rate law for first order kinetics as:
Where,
is the concentration at time t
is the initial concentration
Given that:
The rate constant, k = 0.0231 min⁻¹
Initial concentration
= 7.50 mg
Final concentration
= 0.25 mg
Time = ?
Applying in the above equation, we get that:-

The Curiosity rover found sulfur compounds in rocks and carbon in organic compounds like propane, butene, benzene, toluene and thiophene.
It detected methane, not in soil samples, but in the Martian atmosphere.
It did not discover helium in underground pockets. The hole it can drill is only 5 cm deep.
Answer:
Elements can be described by various properties, and identified by their boiling and melting points. For example, gold melts at
Elements can be described by various properties, and identified by their boiling and melting points. For example, gold melts at 1,064ºC and boils at 2,856ºC. Does boiling point depend on the mass present?
A. No; chemical properties stay the same regardless of mass.
B. No; physical properties stay the same regardless of mass.
C. Yes; physical properties can change when mass increases or decreases.
D. No; qualitative properties like boiling point stay the same regardless of mass.
Explanation:
The answer is B. The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume.
So it contains three protons and four neutrons