A element mixture (key word: mixture) due to the mixture containing 2 different types of elements it can be said that it’s highly likely that the mixture was not a compound but instead of a mixture due to mixture meaning more than 1 material. Hopes this help!
Your Question: There are two kinds of elements that didn't appear on the periodic table until after 1892. What kinds are they and why do you think it took so long to discover them?
The Answer: Moseley’s analysis enabled chemists to refine the table further and reveal more gaps, which suggested that there were more new elements waiting to be discovered, with atomic numbers 43, 61, 72 and 75. Scientists subsequently found these elements—now known as technetium, promethium, hafnium and rhenium, respectively.
Explanation: Physicist Henry Moseley discovered the atomic number of each element using x-rays, which led to more accurate organization of the periodic table. We will cover his life and discovery of the relationship between atomic number and x-ray frequency, known as Moseley's Law.
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Answer: The order of increasing lattice energy is 
Explanation: Lattice energy is defined as the energy required to break the intermolecular force that is responsible for the formation of a lattice.
Melting point is defined as the temperature at which solid gets converted into liquid due to the weakening of the bonds in the solid form.
- Relation between lattice energy and Melting point:
The relationship between these two is direct.
More the melting point of a compound, more will be its lattice energy.
Order of increasing Lattice energy will be:
The answer is A moves molecules. (:
