Unable to locate a dropdown in selenium - selenium-webdriver

Question

I have few fields along with text field ,date, rich text editor, dropdown and browse button to upload image. I am getting error as unable to locate element on selecting the dropdown after rich text editor. Here is my code:
package newpackage;
import java.util.concurrent.TimeUnit;
import org.openqa.selenium.*;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.JavascriptExecutor;
import org.openqa.selenium.support.ui.WebDriverWait;
import org.openqa.selenium.support.ui.ExpectedConditions;
public class MyClass {
public static void main(String args[])throws NoSuchElementException,InterruptedException {
System.setProperty("webdriver.gecko.driver", "C:\\\\geckodriver-v0.18.0-win64\\geckodriver.exe");
WebDriver driver = new FirefoxDriver();
driver.get("url");
driver.findElement(By.id("area_number")).sendKeys("1221");
driver.findElement(By.id("street_name")).sendKeys("abc");
driver.findElement(By.id("email_of_owner")).sendKeys("test#gmail.com");
driver.findElement(By.id("name_of_contact")).sendKeys("Test Papri");
driver.findElement(By.id("contact_date")).click();
driver.findElement(By.xpath("/html/body/div[4]/div/div[2]/button[4]")).click();
WebDriverWait wait = new WebDriverWait(driver,20);
wait.until(ExpectedConditions.visibilityOf(driver.findElement(By.tagName("iframe"))));
//Code for Rich text editor goes here//
jsExecutor.executeScript("window.scrollTo(0, document.body.scrollHeight)");
//Active value is being displayed in a li tag as selected after a button is clicked so tried with this.
WebDriverWait wait1 = new WebDriverWait(driver,30);
wait1.until(ExpectedConditions.elementToBeSelected(By.xpath("/html/body/section[2]/div/div[2]/div/div/div/div[2]/div[1]/form/div[7]/div[2]/div/div/div/div/ul/li[2]/a/span[1]")));
//Select dropdown is a button so tried to click it.This is the xpath of the button
WebElement dropdown = driver.findElement(By.xpath("/html/body/section[2]/div/div[2]/div/div/div/div[2]/div[1]/form/div[7]/div[2]/div/div/div/button"));
//dropdown.click();
//driver.close();
}
}