D. powder residues.
the police and forensic chemists usually perform a qualitative test called GPR or gun powder residue. the residue sticks to the skin.
Answer:
The element is strontium and the number of neutrons it have is 51.
Explanation:
Based on the given information, the ionic compound is,
XCl₂ ⇔ X₂⁺ + 2Cl⁻
X2+ is the ion of the mentioned element
As mentioned in the given question, the number of electrons of the element X is 36 and as seen from the reaction the charge present on the ion is +2. Now the atomic number will be,
No. of electrons = atomic number - charge
36 = atomic number - 2
Atomic number = 38
Based on the periodic table, the atomic number 38 is for strontium element, and the sign of strontium is Sr. Hence, the element X is Sr.
Now based on the given information, the mass number of the element is 89. Now the no. of neutrons will be,
No. of neutrons = mass number - atomic number
= 89 - 38
= 51 neutrons.
Answer:
Scientists debated the theories with each other and compared the theories with scientific observations
Answer:
What is spectrophotometry? It is an analytic method that it use substances light absorbance property
How can this be useful in identifying drugs? It possible compare spectra and identify problem substance
Explanation:
The way substances absorb light is unique and because of that it is possible to use spectrophotometry for substances identifying. the model spectra are measured in ideal conditions, so, it is difficult ensure the same conditions and to achieve identical spectra.
I hope I have been helpful
I believe there are 3 significant figures B.
