A radioactive element is an element which is subject to spontaneous degeneration of its nucleus followed by the emission of alpha, beta and gamma particles. All elements with atomic numbers greater than 83 are radioactive.
The given phrases that describe radioactive elements are-
They have a consistent number of particles
- the particles are alpha, beta and gamma particles.
They have a half-life that determines their rate of decay.
Explanation for other options:
Not all elements occur in nature. Radioactive decay rates may not be constant as the decay happens when a radioactive substance emits a particle. It is not possible to predict exactly when a given atom of a substance will emit a particular particle. When the radioactive element release energy and particles, it decays.
Answer;
The llama and the alpaca were used as beasts of burden in the Andes.
Explanation;
-A beast of burden is drought animal that carries or pulls heavy loads, such as a donkey, mule, llama, camel etc.
-The Andean animal used as a beast of burden is an Alpaca and the Llamas. They are docile, fluffy animals that can withstand the cold of the mountains. As such, they make excellent work animals.
-Male llamas have been been used as beasts of burden in the Peruvian and Bolivian Andes ranges for more than 4000 years.
Every slice of the bread, contains a number of blister like pores. These blister like pores suggests that the air or some gas might be present there. In case, the bread has no air, the surface of the bread must be smooth rather than rough.
The bread is formed by the fermentation of the sugar molecules present in the dough with the help of yeast. These blisters like structure on the bread is present due to the gas produced during fermentation.
The function of a protein is determined by its shape. The shape of a protein is determined by its primary structure (sequence of amino acids). The sequence of amino acids in a protein is determined by the sequence of nucleotides in the gene (DNA) encoding it.
