We can test it becouse in our blood.
You would use both to determine the relative humidity.
A photometer would measure the intensity of light, and a spectrometer would determine which frequencies are present.
Triple beam balance
A mass spectrometer is the instrument used to measure the relative abundance of an isotope. It does this by separating isotopes based on their mass-to-charge ratio and providing a qualitative and quantitative analysis of the isotopic composition of a sample.
To determine the relative density of two immiscible solvents, you would first measure the mass and volume of a known volume of each solvent separately. Calculate the density of each solvent using the formula density = mass/volume. Then, compare the two densities to determine their relative density; the solvent with the greater density will sit below the other when combined in a container. This method allows for a clear understanding of their relative densities without mixing the solvents.
Samples of the rock could be crushed to a fine powder, then separated by magnets to determine the relative percentage of iron.
To determine the relative major key from a minor key, you can find the major key that shares the same key signature. For example, if you are in the key of A minor, the relative major key would be C major because they both have no sharps or flats in their key signature.
To determine the relative humidity of the air, you will need a hygrometer, which is a device that measures humidity. Additionally, a thermometer may be helpful to measure the temperature of the air, as relative humidity changes with temperature. A data logging device or paper and pen to record the measurements would also be necessary.
Mass spectrometer would work.
a ruler and pan balance
Humidity can be directly measured by forced condensation either by pressurized or reduce the temperature and measure the water content directly. Alternative to direct measurement, humidity can be measure using air electro-conductivity since presence of water would increase the conductivity so it could interpret the conductivity to water content.
By using the geologic time scale. Certain organisms are only found during certain times and if a fossil of one of these organisms is found then you can determine the relative age of the fossil.