The value of n in the molecular formula `Be_(n)Al_(2)Si_(6)O_(18)` is:

Explanation

`Be_(n)Al_(2)Si_(6)O_(18)`
`(2n) + (3 xx 2) + (4 xx 6) + (-2 xx 18) = 0 or 2n + 30 - 36 = 0 or 2n = 6 or n = 3`